Technician using microscope for lab testing potential health threats

Lab Testing

Lab Testing

Last Section Update: 03/2026

Contributor(s): Scott Fogle, ND; Shanti Albani, ND; Chancellor Faloon, Health & Wellness Author

Table of Contents

  1. Introduction
  2. Understanding Lab Test Reference Ranges
  3. Recommended Annual Testing
  4. Chemistry Panel and Complete Blood Count: The Most Common Blood Test
  5. General Lab Tests
  6. Anemia and Iron-Related Concerns
  7. Blood Sugar
  8. Adrenal Health
  9. Cardiovascular Health
  10. Digestive Health
  11. Kidney/Liver Health
  12. Thyroid Health
  13. Inflammation
  14. Men’s Health Concerns
  15. Women’s Health Concerns
  16. Update History
  17. References

1 Introduction

Summary and Quick Facts for Lab Testing

  • Lab testing, at least annually, can help you track your health over time and alert you and your doctor to potential health threats.
  • This Protocol provides useful information about several common laboratory tests.
  • When combined with routine doctor visits, regular lab testing can help you plan and implement an evidence-informed health optimization and longevity maximization strategy.

Lab Testing to Optimize Health & Longevity

It is impossible to optimize what you do not measure. Since 1983, Life Extension has suggested that health-conscious individuals undergo yearly lab testing as part of a general health and longevity program. Having annual lab tests can alert you and your doctor to potential health threats and allow you to identify when various health-related parameters deviate from expected normal ranges.

It is important to remember that a single lab result is often not definitive, especially when the value is only slightly outside the reference range. Many reference ranges are defined to include the central 95% of results from a healthy population, which means that, by definition, about 5% of healthy people will have values outside the range (roughly 2.5% below and 2.5% above) for that test. When a person has a broad panel of blood tests repeated over multiple years, the probability of seeing at least one “abnormal” result at some point becomes quite high purely by chance, even in the absence of disease. Lab tests are often more informative when interpreted in context and repeated over time to assess patterns and trends rather than relying on a single isolated value.

This Life Extension Protocol will help you understand the importance of periodic lab testing to monitor your overall health and help you achieve your health goals. We explain many common lab tests and provide context for interpreting “normal” ranges of results. For many of the tests discussed in this Protocol, Life Extension has developed suggested “optimal” ranges. These optimal ranges are based upon our review and interpretation of published scientific evidence and may provide useful benchmarks for individuals pursuing health optimization. Importantly, the “optimal” levels discussed in this Protocol will not be appropriate for or achievable by everyone, and this is more emphatically the case for people with specific health problems or diseases they are managing. You should consult with your qualified healthcare provider regarding the interpretation of your lab test results; you also may wish to consult Life Extension’s team of Wellness Specialists, who have experience interpreting and explaining lab tests results.

Note: Ranges and measurements discussed in this protocol generally apply to tests conducted by Quest Diagnostics and LabCorp. Tests conducted by other labs, such as hospital-based labs, may use different methods and thus have different reference values. Reference ranges based on testing at one lab should not be applied to results obtained via a different lab.

2 Understanding Lab Test Reference Ranges

Why Test Results Can Differ Between Labs

When you have blood work or other laboratory tests done, you may notice that different laboratories (such as Quest Diagnostics, LabCorp, or hospital-based labs) sometimes provide different results for the same test. This is normal and expected. Understanding why this happens can help you better track your health over time.

Different Testing Methods

Clinical laboratories use different instruments, testing methods, and chemical analyzers to measure substances in blood or other samples (Adeli 2017; Vesper 2016). Even when measuring the same thing (like cholesterol or thyroid hormone), different laboratories may use different technologies. These variations in methodology can produce numerically different results, even when testing the exact same sample (Dutta 2009; Stepman 2014).

A reasonable analogy is measuring temperature with different thermometers or measuring temperature at different body sites. One thermometer might read in Fahrenheit while another uses Celsius, or one might be calibrated for use in the ear while the other is calibrated for oral readings. These scenarios all represent valid measures of temperature, but the numbers may not match exactly.

Different Reference Ranges

For many common tests, each laboratory establishes its own "reference range" (also called "normal range") based on the specific testing method they use (Adeli 2017; Doles 2025). These ranges generally reflect lab values that are typically seen in healthy people using that particular lab's equipment and methods.

Reference ranges can vary between laboratories for several reasons (Adeli 2017; Doles 2025; Friedberg 2007):

  • Different testing equipment and methods
  • Different populations used to establish the "normal" range
  • Different manufacturers' recommendations

This means a result that appears "high" at one lab might fall within the "normal" range at another lab. This is not necessarily because your health changed, but may be because the labs use different reference standards.

Lab Results from Different Labs Should Not Be Compared

Because of the differences in methods and reference ranges, it is generally not appropriate to directly compare a test result from one laboratory to a result from a different laboratory (Stepman 2014; Vesper 2016). The numbers may look different, but this does not necessarily mean your health status has changed. The variation might simply reflect differences in how the labs perform the test.

For example, studies have shown that for some common tests like liver enzymes, thyroid hormones, and cholesterol, there can be significant variation between laboratories even when testing the same sample (Dutta 2009; Jansen 2014; Stepman 2014). Hormones are another type of test for which there is often variation between labs.

The Importance of Using the Same Lab for Tracking Over Time

When you need to monitor a health condition over time—such as thyroid function, diabetes control, kidney function, or cholesterol levels—it is important to use the same laboratory consistently (Farrell 2024; Plebani 2016; Van Houcke 2013). This ensures that any changes you see in your results reflect actual changes in your health, not just differences between laboratories.

Using the same lab for ongoing monitoring helps you and your doctor (Bietenbeck 2026; Van Houcke 2013):

  • Accurately track trends in your health
  • Make better treatment decisions
  • Avoid unnecessary worry about changes that are just due to different lab methods
  • Ensure that your results are interpreted against the correct reference range

Once you establish a baseline, use that same lab for all future testing related to the same condition. Keep your lab results so you can monitor trends over time. Importantly, understand that each lab report includes its own reference range—always compare your result to the reference range printed on that specific report. Lastly, do not panic if results look different when you switch labs—discuss any concerns with your doctor, who can interpret the results in context.

Your healthcare team should understand these laboratory differences and be able to help you interpret your results appropriately. By using the same laboratory consistently for monitoring, you help ensure the most accurate tracking of your health over time.

Is Fasting Required Before Routine Blood Testing?

The short answer is: In many cases, no.

It used to be a widespread refrain that fasting overnight for 8– 12 hours was required before most blood tests. This thinking has evolved as evidence has accumulated showing that non-fasting blood testing can reliably provide a good picture of whether most common blood test results are abnormal. This is especially the case for most cases of cholesterol/blood lipid testing (eg, total cholesterol, HDL, LDL, ApoB, etc.). In fact, prominent professional medical and scientific organizations focused on the study of blood lipids have updated recommendations in recent years to state that non-fasting blood testing is appropriate for lipid measurement (Farukhi 2021; Nordestgaard 2016; Wilson 2021; Nordestgaard, 2017).

Moreover, certain goals of testing, such as assessing how your blood sugar responds to a typical meal, need to be done in a non-fasting state by design. For a general assessment of longer-term blood sugar control, a hemoglobin A1C (HbA1C) test is usually the preferred method, and this result does not fluctuate with short-term fasting.

When Fasting is Still Appropriate

Tests specifically intended to follow up on certain potentially abnormal results, or those specifically intended to evaluate fasting biomarkers, may require fasting. For example, confirmation of elevated triglycerides may necessitate a fasting test, and fasting blood glucose testing may be appropriate specifically when blood sugar control is being evaluated. An oral glucose tolerance test (OGTT) also requires fasting.

In general, while fasting is typically not required for routine basic blood testing, refer to documentation and guidance specific to the test you are planning to take for further guidance. Consult a healthcare practitioner for guidance on fasting if you are undergoing blood testing to monitor a specific health concern for which you are receiving care.

3 Recommended Annual Testing

For otherwise healthy adults interested in annual preventive blood testing, Life Extension recommends the following tests. If any abnormalities are discovered on these tests, or if there is reason to suspect any other health issues, then additional tests should be undertaken as appropriate.

Men:

  • Chemistry Panel (metabolic panel with lipids)
  • Complete Blood Count
  • Testosterone (Total)
  • Free Testosterone
  • Dehydroepiandrosterone sulfate (DHEA-S)
  • Prostate Specific Antigen (PSA)
  • Estradiol (E2)
  • Homocysteine
  • C-reactive protein (High sensitivity)
  • TSH (Thyroid stimulating hormone)
  • Vitamin D, 25-Hydroxy
  • Hemoglobin A1C (HbA1C)
  • Apolipoprotein B (ApoB)

Women:

  • Chemistry Panel (metabolic panel with lipids)
  • Complete Blood Count
  • Testosterone (Total)
  • Free Testosterone
  • Dehydroepiandrosterone sulfate (DHEA-S)
  • Progesterone
  • Estradiol (E2)
  • Homocysteine
  • C-reactive protein (High sensitivity)
  • TSH (Thyroid stimulating hormone)
  • Vitamin D, 25-Hydroxy
  • Hemoglobin A1C (HbA1C)
  • Apolipoprotein B (ApoB)

4 Chemistry Panel and Complete Blood Count: The Most Common Blood Test

Hematocrit (whole blood)

Hematocrit measures the percentage of whole blood that is made up of red blood cells. Hematocrit decreases with age (Kubota 1991) and in anemia and increases in dehydration, and high values were also associated with the possibility of an increased risk for venous thrombosis (Schreijer 2010). Low or high hematocrit levels are associated with increased morbidity and mortality (Boffetta 2013; Paller 2012).

Quest Diagnostics LabCorp
Test Method:
  • Electronic Cell, Sizing/Cytometry/Microscopy
Test Method:
  • Automated cell counter

Reference Range:

  • Women: 35%–45%
  • Men: 38.5%–50%

Reference Range:

  • Women: 34%–46.6%
  • Men: 37.5%–51%

Life Extension’s Suggested Optimal Range:

  • Mid-range for both men and women

Life Extension’s Suggested Optimal Range:

  • Upper end of reference range for both men and women

Hemoglobin (whole blood)

Hemoglobin is the iron-containing oxygen-transport protein in red blood cells. Its measurement aids in the diagnosis of various forms of anemia.

Quest Diagnostics LabCorp

Test Method:

  • Electronic Cell, Sizing/Cytometry/Microscopy

Test Method:

  • Automated cell counter

Reference Range:

  • Women: 11.7–15.5 g/dL
  • Men: 13.2–17.1 g/dL

Reference Range:

  • Women: 11.5–15.9 g/dL
  • Men: 12.6–17.7 g/dL

Life Extension’s Suggested Optimal Range:

  • Mid-range

Life Extension’s Suggested Optimal Range:

  • Upper end of reference range

Sodium (serum)

Sodium is an essential electrolyte that is vital to normal cell function and to fluid, acid-base, and electrolyte balance. It also plays an important role in nerve and muscle function as well as nutrient transport (Strazzullo 2014). Serum sodium levels can reflect hydration status, kidney function, and other important medical information (BMJ Best Practice 2021; Wojszel 2020). A study published in early 2023 reported an association between serum sodium levels above 142 mmol/L in individuals aged 45-66 and an increased risk of chronic diseases. This study also reported an increased mortality risk associated with serum sodium levels above 144 mmol/L. The investigators remarked that their results suggest a serum sodium range of 138-142 mmol/L is associated with the lowest risk of chronic disease and death (Dmitrieva 2023).

Quest Diagnostics LabCorp
Test Method:
  • Ion-selective electrode (ISE)
Test Method:
  • Ion-selective electrode (ISE); flame photometer
Reference Range:
  • 135–146 mmol/L
Reference Range:
  • 134–144 mmol/L
Life Extension’s Suggested Optimal Range:
  • 138–142 mmol/L (If >142 consider dehydration)
Life Extension’s Suggested Optimal Range:
  • 138–142 mmol/L (If >142 consider dehydration)

Calcium (serum)

This test is used to evaluate parathyroid function and calcium metabolism. Serum calcium is increased in hyperparathyroidism, hyperthyroidism, metabolic diseases of the bone, immobilization after trauma or osteoporosis, leukemia, lymphoma, and the use of certain diuretics (Goldstein 1990).

Quest Diagnostics LabCorp
Test Method:
  • Spectrophotometry (SP)
Test Method:
  • Colorimetric
Reference Range:
  • Women: 8.6–10.2 mg/dL (20-49y)
    8.6–10.4 mg/dL (>49y)
  • Men: 8.6–10.3 mg/dL (>20y)
Reference Range:
  • 8.7–10.2 (18-59y)
Life Extension’s Suggested Optimal Range:
  • 8.6–10 mg/dL (>40y)
Life Extension’s Suggested Optimal Range:
  • 9–10 mg/dL (>40y)

Albumin (serum or plasma)

Increased albumin is found in cases of dehydration. Low albumin is found in patients receiving intravenous fluids, excessive hydration, liver disease, chronic alcoholism, certain chronic diseases such as cancer, Crohn’s disease, ulcerative colitis, chronic inflammatory diseases, infections, heart failure, skin diseases, burns, pregnancy, and oral contraceptive use.

Quest Diagnostics LabCorp

Test Method:

  • Spectrophotometry (SP)

Test Method:

  • Colorimetric

Reference Range:

  • 3.6–5.1 g/dL

Reference Range:

  • 3.5–5.5 g/dL

Glucose (serum)

High blood glucose levels are associated with diabetes, neuropathy, eye problems, heart disease, and stroke. Glucose is the primary blood sugar used by cells to make energy. Glucose level is included in most chemistry panels. It is useful to have glucose tested with other measures such as insulin and hemoglobin A1C (HbA1C). This test may be done fasting or 2‒4 hours after eating. Both types of tests provide valuable information, though 2‒4 hours after a meal provides a more realistic assessment of the state of your blood in everyday life.

Quest Diagnostics LabCorp

Test Method:

  • Spectrophotometry (SP)

Test Method:

  • Enzymatic

Reference Range:

  • 65–99 mg/dL

Reference Range:

  • 70–99 mg/dL

Life Extension’s Suggested Optimal Range:

  • 80–86 mg/dL

Life Extension’s Suggested Optimal Range:

  • 80–86 mg/dL

Uric Acid (serum or plasma)

Uric acid is made from purines, which are made naturally in the body and also come from the diet (Schlesinger 2005). If uric acid is overproduced or the kidneys are unable to get rid of it, the elevated levels can result in joint pain, leading to a condition known as gout (George 2017). Uric acid is included in most chemistry panels.

Quest Diagnostics LabCorp

Test Method:

  • Spectrophotometry (SP)

Test Method:

  • Uricase

Reference Range:

  • Women 2.5–7 mg/dL
  • Men 4–8 mg/dL

Reference Range:

  • Women 2.6–6.2 mg/dL (18-50y)
    3.0–7.2 (51-70y)
    3.1–7.9 (>70y)
  • Men 3.8–8.4 mg/dL

Life Extension’s Suggested Optimal Range:

  • <6 mg/dL

Life Extension’s Suggested Optimal Range:

  • <6 mg/dL

Creatinine (serum or plasma)

Creatinine is a commonly used test to evaluate kidney function by measuring the rate of filtered fluid through the kidneys (Gowda 2010). It is included in most chemistry panels along with the BUN/creatinine ratio (which has a reference range of 9-20).

Quest Diagnostics LabCorp

Test Method:

  • Spectrophotometry (SP)

Test Method:

  • Enzymatic (creatinase)/spectrophotometry
Reference Range:

Reference Range:

 

 Men (mg/dL) Women (mg/dL)
  • Women: 0.57–1.0 mg/dL
  • Men: 0.76–1.27 mg/dL
    • 18–29 years 0.60–1.24 0.50–0.96
    30–39 years 0.60–1.26 0.50–0.97
    40–49 years 0.60–1.29 0.50–0.99
    50–59 years 0.70–1.30 0.50–1.03
    50–59 years 0.70–1.30 0.50–1.03
    60–69 years 0.70–1.35 0.50–1.05
    70–79 years 0.70–1.35 0.60–1.00
    ≥80 years 0.70–1.22 0.60–0.95

    Blood Urea Nitrogen (BUN) (serum or plasma)

    Blood urea nitrogen (BUN) is an indicator of how well the liver and kidneys are functioning. BUN is included in most chemistry panels along with the BUN/creatinine ratio.

    Quest Diagnostics LabCorp

    Test Method:

    • Spectrophotometry (SP)

    Test Method:

    • Enzymatic (urease)

    Reference Range:

    • 7–25 mg/dL (≥20y)

    Reference Range:

    • 6–20 mg/dL (adults)
    • 8–23 mg/dL (>60y)

    Total Cholesterol/HDL Cholesterol Ratio (serum or plasma)

    The total cholesterol to HDL cholesterol ratio is helpful in predicting an individual’s risk of developing atherosclerosis. The number is obtained by dividing the total cholesterol value by the value of the HDL cholesterol. (High ratios indicate higher risks of heart attacks; low ratios indicate lower risk.)

    Quest Diagnostics LabCorp

    Test Method:

    • Calculated

    Test Method:

    • Calculated

    Reference Range:

    • <5.0 mg/dL

    Reference Range:

    • Women: 3.3 mg/dL (1/2 average risk); 4.4 mg/dL (average risk); 7.1 mg/dL (2x average risk)
    • Men: 3.4 mg/dL (1/2 average risk); 5 mg/dL (average risk); 9.6 mg/dL (2x average risk)

    Life Extension’s Suggested Optimal Range:

    • <3.5 mg/dL

    Life Extension’s Suggested Optimal Range:

    • <3.4 mg/dL

    Triglycerides (serum or plasma)

    Triglyceride levels are used to identify risk for developing coronary heart disease and if fat metabolism disorders are suspected.

    Quest Diagnostics LabCorp

    Test Method:

    • Spectrophotometry (SP)

    Test Method:

    • Enzymatic

    Reference Range:

    • <150 mg/dL

    Reference Range:

    • <150 mg/dL

    Life Extension’s Suggested Optimal Range:

    • <100 mg/dL
    • <80 mg/dL (best if any risk factors)

    Life Extension’s Suggested Optimal Range:

    • <100 mg/dL
    • <80 mg/dL (best if any risk factors)

    Total Cholesterol (serum or plasma)

    Total cholesterol is used to assess risk of coronary heart disease and stroke (Kinosian 1994; Ansell 2000; Foroughi 2013).

    Quest Diagnostics LabCorp

    Test Method:

    • Spectrophotometry (SP)

    Test Method:

    • Enzymatic

    Reference Range:

    • <200 mg/dL

    Reference Range:

    • 100–199 mg/dL (over age 19y)

    Life Extension’s Suggested Optimal Range:

    • 160–180 mg/dL

    Life Extension’s Suggested Optimal Range:

    • 160–180 mg/dL

    HDL (serum or plasma)

    High-density lipoprotein (HDL) is known as the “good” cholesterol because it helps transport cholesterol from cells to the liver for removal. Low HDL levels are used as a predictor of heart disease risk.

    Quest Diagnostics LabCorp

    Test Method:

    • Spectrophotometry (SP)

    Test Method:

    • Enzymatic

    Reference Range:

    • Women: ≥50 mg/dL
    • Men: ≥40 mg/dL

    Reference Range:

    • >39 mg/dL

    Life Extension’s Suggested Optimal Range:

    • ≥50 mg/dL

    Life Extension’s Suggested Optimal Range:

    • ≥50 mg/dL

    LDL (serum or plasma)

    Low-density lipoprotein (LDL) is known as the “bad” cholesterol because it carries cholesterol and fats from the liver to the rest of the body. Elevated LDL levels are used as a predictor of heart disease risk.

    Quest Diagnostics LabCorp

    Test Method:

    • Martin-Hopkins Calculation

    Test Method:

    • NIH LDL-C equation

    Reference Range:

    • <100 mg/dL

    Reference Range:

    • 0–99 mg/dL (over age 19y)

    Life Extension’s Suggested Optimal Range:

    • 80–100 mg/dL (good)
    • 40–80 mg/dL (better)

      • (Individuals with pre-existing CVD may need to target the lower end of the range, but that should be discussed with their physician)

    Life Extension’s Suggested Optimal Range:

    • 80–100 mg/dL (good)
    • 40–80 (better)

      • (Individuals with pre-existing CVD may need to target the lower end of the range, but that should be discussed with their physician)

    Iron (serum, preferred)

    Low levels of iron are associated with iron deficiency anemia. Anemia is associated with fatigue, low energy, and in some cases, can manifest as muscle aches and headaches. High levels of iron are associated with liver disease, kidney disease, and vitamin B6 deficiency (Prothro 1981; Gkamprela 2017; Mydlik 1997).

    Quest Diagnostics LabCorp

    Test Method:

    • Spectrophotometry (SP)

    Test Method:

    • Colorimetric

    Reference Range:

    • Women: 40-190 µg/dL (20-49y)
      45-160 µg/dL (>50y)
    • Men: 50-195 µg/dL (20-29y)
      50-180 µg/dL (>30y)

    Reference Range:

    • Women: 27-159 µg/dL
    • Men: 38-169 µg/dL

    Life Extension’s Suggested Optimal Range:

    • Women: 40-100 µg/dL
    • Men: 50-100 µg/dL

    Life Extension’s Suggested Optimal Range:

    • 40-100 µg/dL

    5 General Lab Tests

    Gamma-globulin (serum)

    Increased gamma-globulin is found in certain chronic inflammatory or autoimmune conditions, certain cancers, acute infections, chronic liver disease, and an overactive immune system.

    Quest Diagnostics LabCorp

    Test Method:

    • Spectrophotometry (SP)

    Test Method:

    • Colorimetric

    Reference Range:

    • 0.8–1.7 g/dL

    Reference Range:

    • 0.4–1.8 mg/dL

    Magnesium (serum)

    Magnesium is one of the body’s most important minerals. It is required as a co-factor in hundreds of enzymatic processes within cells. It helps maintain normal muscle and nerve function, keeps heart rhythm steady, is necessary for healthy cardiovascular function, supports a healthy immune system, and keeps bones strong (Galland 1988; Jahnen-Dechent 2012; Castiglioni 2013). Magnesium also helps maintain healthy blood sugar and blood pressure levels and is involved in energy metabolism and protein synthesis (Cinar 2008; Veronese 2016; Guerrero-Romero 2009).

    Quest Diagnostics LabCorp

    Test Method:

    • Spectrophotometry (SP)

    Test Method:

    • Colorimetric

    Reference Range:

    • 1.5–2.5 mg/dL

    Reference Range:

    • 1.6–2.3 mg/dL

    Life Extension’s Suggested Optimal Range:

    • 2.07–2.5 mg/dL

    Life Extension’s Suggested Optimal Range:

    • 2.07–2.31 mg/dL

    Magnesium (RBC)

    Red blood cell (RBC) magnesium is the most precise way to assess intracellular magnesium status, and free RBC magnesium has been shown to be inversely related with hypertension (Resnick 1984; Geiger 2012; Rosanoff 2005; Volpe 2013).

    Quest Diagnostics LabCorp

    Test Method:

    • Inductively coupled plasma mass spectrometry (ICP/MS)

    Test Method:

    • Atomic absorption spectroscopy (AAS); Inductively coupled plasma mass spectrometry (ICP/MS)

    Reference Range:

    • 4.0–6.4 mg/dL

    Reference Range:

    • 4.2–6.8 mg/dL

    Life Extension’s Suggested Optimal Range:

    • 5.6–6.4 mg/dL (Upper 3 rd of range)

    Life Extension’s Suggested Optimal Range:

    • >6.0 mg/dL

    Selenium (serum or plasma)

    Selenium is a trace mineral and one of the body’s critical defenses against oxidative stress (Tinggi 2008; Rayman 2000). Selenium is incorporated into proteins to make selenoproteins, which are important free-radical quenching enzymes (Genc 2017). Selenium has also been shown to help regulate thyroid function and play a role in the immune system, DNA repair, and detoxification of heavy metals (Hoffmann 2008; Bera 2013; Whanger 1992; Ventura 2017).

    Quest Diagnostics LabCorp

    Test Method:

    • Inductively Coupled Plasma/Mass Spectrometry (ICP/MS)

    Test Method:

    • Inductively coupled plasma/mass spectrometry (ICP/MS)

    Reference Range:

    • 63–160 µ/L

    Reference Range:

    • 91–198 µg/L

    Vitamin C (serum)

    Vitamin C (ascorbic acid) is one of the body’s most important defenses against oxidative stress (Sorice 2014). Vitamin C is critical for protection against damaging free radicals, and is essential for tissue healing, immune function, fertility, cardiovascular health, and prevention of the common cold (Hemila 1992; Padh 1991; Bendich 1995; Chambial 2013). Low values occur in scurvy (Burhop 2018), malabsorption syndromes (Lykkesfeldt 2014), inflammatory bowel disease (Imes 1986), alcoholism (Majumdar 1981), pregnancy (IOM 1990), certain thyroid conditions (Moncayo 2008), and kidney failure (Granata 2015). Smokers have also been shown to have lower levels than non-smokers (Schectman 1989; Smith 1987).

    Quest Diagnostics LabCorp

    Test Method:

    • Chromatography-Mass Spectrometry

    Test Method:

    • Liquid chromatography-tandem mass spectrometry (LC/MS-MS)

    Reference Range:

    • Women: 0.3–2.1 mg/dL
    • Men: 0.2–2.1 mg/dL

    Reference Range:

    • 0.2–2.0 mg/dL

    Life Extension’s Suggested Optimal Range:

    • >1.2 mg/dL

    Life Extension’s Suggested Optimal Range:

    • >1.2 mg/dL

    Vitamin D, 25-Hydroxy (serum)

    Vitamin D is essential for human life, so much so that our bodies manufacture this critical nutrient in the skin upon sun exposure (Nair 2012). However, most people do not get enough sun exposure to maintain optimal levels of vitamin D in their bodies; risks of skin cancer and sun damage dissuade many of us from spending much time in the sun (Norman 2008).

    But sun exposure is not the only way to increase vitamin D levels. Supplemental vitamin D efficiently boosts blood levels of vitamin D, which are typically measured as 25-hydroxyvitamin D. This is fortunate because research over many years has firmly established vitamin D as a key mediator of health throughout the body. Classically, vitamin D was thought to primarily support calcium homeostasis, but it is now known that vitamin D has many other crucial functions, including helping to balance the immune system (Bscheider 2016), suppress abnormal cell growth (Ness 2015; Watanabe 2015), and support brain health (Groves 2014).

    Vitamin D deficiency has been associated with a host of diseases ranging from cancer (Kurylowicz 2007; Nabi 2015) and cardiovascular disease (Mozos 2015) to osteoporosis (Sahota 2000) and cognitive impairment (Etgen 2012). Thus, maintaining an optimal blood level of 25-hydroxyvitamin D is of paramount importance.

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Immunochemiluminometric assay (ICMA)

    Reference Range:

    • 30–100 ng/mL

    Reference Range:

    • 30–100 ng/mL

    Life Extension’s Suggested Optimal Range:

    • 50–80 ng/mL

    Life Extension’s Suggested Optimal Range:

    • 50–80 ng/mL

    Zinc (serum or plasma)

    This test is used to evaluate zinc deficiencies since the body does not store this important mineral (Jurowski 2014). Levels may be low in malnutrition, malabsorption, alcoholism, extensive burns, some chronic and genetic conditions, and after the use of certain drugs (Prasad 1985), estrogen therapy (Herzberg 1996), and in anxiety, depression and stress (Gronli 2013; Russo 2011), and heart disease (Hashemian 2015). Zinc deficiencies may result in abnormal development (Black 1998), poor immune function (Prasad 2008), and hormone imbalances (Favier 1992). Additionally, people with low levels of zinc often report altered taste and smell (Tomita 1996), impaired night vision (Miao 2013), and emotional instability (Russo 2011).

    Quest Diagnostics LabCorp

    Test Method:

    • Inductively coupled plasma mass spectrometry (ICP/MS)

    Test Method:

    • Inductively coupled plasma mass spectrometry (ICP/MS)

    Reference Range:

    • 60–130 µ/dL

    Reference Range:

    • 44–115 µg/dL

    Life Extension’s Suggested Optimal Range:

    • >95 µ/dL

    Life Extension’s Suggested Optimal Range:

    • >85 µg/dL

    6 Anemia and Iron-Related Concerns

    Ferritin (serum)

    Iron is stored mostly in the liver bound to the protein ferritin. The amount of ferritin found in the blood shows how much iron is stored in the body (Knovich 2009).

    Quest Diagnostics LabCorp

    Test Method:

    • Photometry/Optical, Clauss

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • Women: 16–154 ng/mL (19-40y)
    • Men: 24–380 ng/mL (19-50y)
      24–380 ng/mL (>59y)

    Reference Range:

    • Women: 15–150 ng/mL
    • Men: 30–400 ng/mL

    Life Extension’s Suggested Optimal Range:

    • Women: 50–100 ng/mL
    • Men: 50–125 ng/mL

    Life Extension’s Suggested Optimal Range:

    • Women: 50–100 ng/mL
    • Men: 50–125 ng/mL

    Vitamin B12 (serum)

    Vitamin B12 plays an important role in producing cellular energy, for the formation of red blood cells, the functioning of the nervous system, including learning and memory (Kobe 2016; Grober 2013; Leishear 2012; O'Leary 2010). Vitamin B12 testing helps diagnose central nervous system disorders, anemia, and malabsorption syndromes.

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • 200–1,100 pg/mL

    Reference Range:

    • 232–1,245 pg/mL

    Life Extension’s Suggested Optimal Range:

    • >400 pg/mL

    Life Extension’s Suggested Optimal Range:

    • >400 pg/mL

    7 Blood Sugar

    Fasting Glucose (serum)

    High blood glucose levels are associated with diabetes, neuropathy, eye problems, heart disease, and stroke. Glucose is the primary blood sugar used by cells to make energy. Glucose level is included in most chemistry panels. It is useful to have glucose tested with other measures such as insulin and hemoglobin A1C (HbA1C). This test may be done fasting or 2‒4 hours after eating. Both types of tests provide valuable information, though 2‒4 hours after a meal provides a more realistic assessment of the state of your blood in everyday life.

    Quest Diagnostics LabCorp

    Test Method:

    • Spectrophotometry (SP)

    Test Method:

    • Enzymatic

    Reference Range:

    • 65–99 mg/dL

    Reference Range:

    • 70–99 mg/dL

    Life Extension’s Suggested Optimal Range:

    • 80–86 mg/dL

    Life Extension’s Suggested Optimal Range:

    • 80–86 mg/dL

    Glucose (2-Hour Postprandial) (serum or plasma)

    Normally, blood glucose levels increase slightly after you eat. This increase causes the pancreas to release insulin so blood glucose levels do not get too high. Blood glucose levels that remain high over time can damage your eyes, kidneys, nerves, and blood vessels. This test measures blood glucose exactly two hours after eating.

    Quest Diagnostics LabCorp

    Test Method:

    • Spectrophotometry (SP)

    Test Method:

    • Enzymatic

    Reference Range:

    • 65–139 mg/dL
      (140–149 = impaired glucose tolerance; > 200 = provisional evidence of glucose tolerance)

    Reference Range:

    • 65–139 mg/dL
      (140–149 = impaired glucose tolerance; > 200 = provisional evidence of glucose tolerance)

    Life Extension’s Suggested Optimal Range:

    • 120–140 mg/dL (good)
    • 110–125 mg/dL (ideal)
      (<40 increase over baseline)

    Life Extension’s Suggested Optimal Range:

    • 120–140 mg/dL (good)
    • 110–125 mg/dL (ideal)
      (<40 increase over baseline)

    Hemoglobin A1C (whole blood)

    Hemoglobin A1C (HbA1C) evaluates long-term blood sugar control and correlates well with the risk of complications from diabetes (Sherwani 2016). Serum glucose reacts with important proteins in the body rendering them nonfunctional in a process called glycation. HbA1C is a reflection of this detrimental reaction (Florkowski 2013). Doctors often follow this blood test in diabetics to monitor disease progression and the effects of treatment.

    Quest Diagnostics LabCorp

    Test Method:

    • Electronic Cell, Sizing/Cytometry/Microscopy

    Test Method:

    • Automated cell counter

    Reference Range:

    • Women: 11.7–15.5 g/dL
    • Men: 13.2–17.1 g/dL

    Reference Range:

    • Women: 11.5–15.9 g/dL
    • Men: 12.6–17.7 g/dL

    Life Extension’s Suggested Optimal Range:

    • Mid-range

    Life Extension’s Suggested Optimal Range:

    • Upper end of reference range

    Fasting Insulin (serum)

    Insulin is a hormone secreted by the pancreas in response to eating carbohydrates. Insulin facilitates the transport of carbohydrates and sugars from the bloodstream into the cells. Insulin resistance, the hallmark of type II diabetes, occurs with excessive carbohydrate intake. In this case, insulin does not work optimally to drive glucose into the cells and tissues and results in high blood glucose. This test may be done fasting or 2‒6 hours after eating. Both ways provide valuable information, though 2‒6 hours after a meal provides a more realistic assessment of the state of your blood in everyday life.

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • ≤18.4 µIU/mL

    Reference Range:

    • 2.6–24.9 µIU/mL

    Life Extension’s Suggested Optimal Range:

    • <5 µIU/mL

    Life Extension’s Suggested Optimal Range:

    • <5–7 µIU/mL is ideal

    Additional information about the importance of maintaining healthy blood sugar levels can be found in the Diabetes and Glucose Control protocol.

    8 Adrenal Health

    Cortisol (serum)

    Cortisol is the major adrenal steroid hormone and is controlled by the pituitary gland and the hypothalamus. The body’s stress response increases cortisol in order to mobilize energy to manage and resolve the stressor.

    Chronic stress can fatigue the adrenal gland which can disrupt its normal diurnal control over cortisol. This disruption can lead to symptoms like fatigue, weight gain, insomnia, depression, and anxiety.

    Typically, cortisol is highest in the morning and drops during the day for most people (Chan 2010). Some people have a “reverse” cortisol rhythm or curve, where the levels are higher at night instead of being highest in the morning. Obtaining a morning and late afternoon cortisol value provides more information regarding an individual’s daily fluctuation in cortisol.

    Cortisol can be measured at a single point during the day, or in the morning and again in the afternoon to get a better idea of its fluctuations.

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • AM: 4.0–22.00 μg/dL
    • PM: 3.0–17.00 μg/dL

    Reference Range:

    • AM: 6.2–19.4 μg/dL
    • PM: 2.3–11.9 μg/dL

    Dehydroepiandrosterone Sulfate (serum)

    Dehydroepiandrosterone sulfate (DHEA-S) is a precursor for the sex steroids including estrogen and testosterone (Dimitrakakis 2009). DHEA-S and DHEA are primarily produced in the adrenal gland, and DHEA is produced by the ovary and testis (Crawford 2009; Maninger 2009). DHEA-S plays an important role in immune function and stress response (do Vale 2014; Buford 2008). Low DHEA-S levels are associated with a shorter lifespan, while higher levels are a predictor of longevity (Leowattana 2001; Rutkowski 2014).

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • Men:
      20–480 µg/dL (18–21y)
      74–617 µg/dL (22–30y)
      93–415 µg/dL (31–40y)
    • Women:
      44–286 µg/dL (18–21y)
      14–349 µg/dL (22–30y)
      19–237 µg/dL (31–40y)

    Reference Range:

    • Men:
      164.3–530.5 µg/dL (20–24y)
      138.5–475.2 µg/dL (25–34y)
    • Women:
      110–431.7 µg/dL (20–24y)
      84.8–378 µg/dL (25–34y)

    Life Extension’s Suggested Optimal Range:

    • Men: 350–500 µg/dL
    • Women: 180–350 µg/dL

    Life Extension’s Suggested Optimal Range:

    • Men: 350–500 µg/dL
    • Women: 275–400 µg/dL

    9 Cardiovascular Health

    Oxidized LDL

    Oxidized LDL, the “bad” cholesterol that has been modified by oxidation, triggers inflammation leading to the formation of plaque in the arteries. High levels of oxidized LDL are associated with an increased risk of metabolic syndrome and coronary artery disease. Oxidized LDL is often measured with myeloperoxidase and/or F2-isoprostanes.

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Enzyme-linked immunoassay (ELISA)

    Reference Range:

    • <60 U/L

    Reference Range:

    • 10–170 ng/mL

    Myeloperoxidase

    Myeloperoxidase (MPO) is an enzyme released by white blood cells when they attack. It causes death to microbes and amplifies inflammation and immune cell recruitment. This is great if there is a foreign invader, but terrible if it is happening in the arteries in response to oxidized LDL. It amplifies inflammation there and causes problems that increase plaque and often the worse kind of plaque, the soft vulnerable plaque that is prone to rupture. To make matters worse, MPO also oxidizes LDL, making it more plaque-promoting, and even oxidizes HDL (ie, good cholesterol) rendering it dysfunctional so it can no longer be helpful. These effects result in inflammation linked to plaque buildup inside the artery wall. Thus, MPO is a very interesting cardiovascular marker that is worth checking, especially in those with family history of cardiovascular disease or who make poor lifestyle choices.

    Quest Diagnostics LabCorp

    Test Method:

    • Turbidimetric Immunoassay

    Test Method:

    • Latex enhanced immunoturbidimetric method

    Reference Range:

    • <470 pmol/L

    Reference Range:

    • Low CVD risk: <470 pmol/L
    • Moderate CVD risk: 470–539 pmol/L
    • High CVD risk: >539 pmol/L

    F2-Isoprostanes (Urinary Test)

    F2-Isoprostanes (F2-IsoPs) are a biomarker for oxidative stress. Oxidative stress occurs when free radicals react with neighboring molecules causing a cascade of damage in cells, which initiates destructive pathways that can lead to heart disease. F2-IsoPs may be elevated at the earliest stages of plaque development. F2-IsoPs are often measured along with oxidized LDL and/or MPO.

    Quest Diagnostics LabCorp

    Test Method:

    • Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS)

    Test Method:

    • Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS)

    Reference Range:

    • Low Risk < 0.86 ng/mg
    • High Risk ≥ 0.86 ng/mg

    Reference Range:

    • Low Risk < 0.86 ng/mg
    • High Risk ≥ 0.86 ng/mg

    Lipoprotein (a) (serum or plasma)

    Elevated lipoprotein (a) is a strong indicator of premature coronary disease and atherosclerotic vascular disease and is associated with increased risk of cardiac death in patients with coronary heart disease and stroke (Erqou 2009).

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoturbidimetric

    Test Method:

    • Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)

    Reference Range:

    • <75 nmol/L

    Reference Range:

    • <75 nmol/L

    Apolipoprotein B (ApoB)

    The apolipoprotein B (apo B) blood test measures the number of potentially dangerous lipoprotein particles that can lead to the atherosclerotic process.

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoturbidimetric

    Test Method:

    • Immunologic

    Reference Range:

    • <90 mg/dL

    Reference Range:

    • Desirable: <90 mg/dL
    • Borderline: High: 90–99 mg/dL
    • High: 100–130 mg/dL
    • Very High: >130 mg/dL

    Life Extension’s Suggested Optimal Range:

    • <90 mg/dL
    • <60 mg/dL (for those with high risk of arterial occlusion)

    Life Extension’s Suggested Optimal Range:

    • <90 mg/dL
    • <60 mg/dL (for those with high risk of arterial occlusion)

    Coenzyme Q10 (plasma, frozen and protected from light)

    Coenzyme Q10 (CoQ10) is produced by the human body and is necessary for the basic functioning of all cells. It is known to be highly concentrated in heart muscle cells due to the high energy requirements of this cell type (Fotino 2013).

    CoQ10 blood levels are reported to decrease with age and to be low in patients with chronic diseases such as heart conditions, neuromuscular diseases, Parkinson disease, cancer, diabetes, and HIV/AIDS. Some prescriptions like statin medications can also lower CoQ10 levels (DiNicolantonio 2015; Artuch 2009; Mischley 2012; Cobanoglu 2011; Chai 2010; Folkers 1988; Shen 2015).

    Quest Diagnostics LabCorp

    Test Method:

    • Liquid chromatography-tandem mass spectrometry (LC/MS-MS)

    Test Method:

    • Liquid chromatography-tandem mass spectrometry (LC/MS-MS)

    Reference Range:

    • >0.35 µg/mL

    Reference Range:

    • 0.37–2.20 µg/mL

    Life Extension’s Suggested Optimal Range:

    • 3–7 µg/mL (those with cardiovascular disease or neurodegenerative disease likely need to be at the upper end of the optimal range)

    Life Extension’s Suggested Optimal Range:

    • 3–7 µg/mL (those with cardiovascular disease or neurodegenerative disease likely need to be at the upper end of the optimal range)

    Fibrinogen Activity (whole blood or plasma)

    Fibrinogen is a key clotting protein that is an independent risk factor for cardiovascular disease and ischemic stroke (Franchini 2012; Montalescot 1998; Fukujima 1997).

    Quest Diagnostics LabCorp

    Test Method:

    • Photometry/Optical, Clauss

    Test Method:

    • Liquid chromatography-tandem mass spectrometry (LC/MS-MS)

    Reference Range:

    • 175–425 mg/dL

    Reference Range:

    • 193–507 mg/dL

    Life Extension’s Suggested Optimal Range:

    • 295–369 mg/dL

    Life Extension’s Suggested Optimal Range:

    • 295–369 mg/dL

    Homocysteine (plasma; serum is acceptable)

    Homocysteine is an independent risk factor for coronary heart disease. High blood levels may directly damage the delicate endothelial cells that line the inside of arteries and result in vascular inflammation, blood clot formation, and arterial plaque rupture. Studies have shown that even moderate levels of homocysteine pose an increased risk for arterial plaque formation when compared with the lowest 20th percentile (<7.2 µmol/L) of population controls.

    Quest Diagnostics LabCorp

    Test Method:

    • Enzymatic

    Test Method:

    • Enzymatic

    Reference Range:

    • Women:
      ≤10.9 µmol/L (18–29 y)
      ≤ 11 µmol/L (30–49 y)
      ≤ 13.4 µmol/L (>49 y)
    • Men:
      ≤12.9 µmol/L (18–29 y)
      ≤ 13.5 µmol/L (30–49 y)
      ≤ 15.2 µmol/L (>49 y)

    Reference Range:

    • Men and Women:
      0.0–14.5 µmol/L (18-60y)
      0.0–17.2 µmol/L (61-70y)
      0.0–19.2 µmol/L (71-80y)
      0.0–21.3 µmol/L (>80y)

    Life Extension’s Suggested Optimal Range:

    • 12 µmol/L
    • <8 µmol/L (ideal)

    Life Extension’s Suggested Optimal Range:

    • 12 µmol/L
    • <8 µmol/L (ideal)

    Additional information about methods for maintaining cardiovascular health can be found in the Atherosclerosis and Cardiovascular Disease protocol.

    10 Digestive Health

    Small Intestinal Bacterial Overgrowth (SIBO) Breath Test – Lactulose

    At-home breath tests can help determine some of the causes of digestive distress. Small intestinal bacterial overgrowth (SIBO) occurs when intestinal bacteria overgrow in the small intestine (Bures 2010; Dukowicz 2007; Bayeli 1999). This overgrowth can lead to excess production of gas and bacterial metabolites, causing bloating, flatulence, diarrhea, constipation, and cramping (Sachdev 2013). Lactulose has the advantage of detecting bacterial overgrowth throughout the small intestine, including the lower end where it more commonly occurs. Humans cannot digest or absorb lactulose, and only bacteria have the proper enzymes to break it down (Chen 2012). Lactulose passes unabsorbed through the normal small intestine, and when it reaches the colon, it is metabolized by bacteria to gases, including hydrogen, which can be detected (Simren 2006; Saad 2014).

    Small Intestinal Bacterial Overgrowth (SIBO) Breath Test – Glucose

    Although glucose is highly fermentable by bacteria, it is typically absorbed in the upper portion of the small intestine and thus, SIBO existing in the lower portion of the small intestines may be missed (Mattsson 2017; Chen 2016; Kiela 2016). The glucose breath test is more accurate than the lactulose breath test, and is considered more acceptable for diagnosing SIBO (Enko 2016; Rana 2014; Ghoshal 2011; Saad 2014). The test can also give false-positive results if the oral bacteria flora produces hydrogen (Mattsson 2017).

    11 Kidney/Liver Health

    Cystatin C (serum or plasma)

    Cystatin-C is an indicator of kidney function (Murty 2013). It has been suggested that cystatin-C might predict patients with “preclinical” kidney dysfunction and patients with chronic kidney disease who are at a higher risk of complications (Shlipak 2006; Peralta 2011). Moreover, it can predict the risk of death and cardiovascular complications in patients with chronic kidney disease (Vigil 2014).

    Quest Diagnostics LabCorp

    Test Method:

    • Latex particle-enhanced turbidimetric immunoassay (PETIA)

    Test Method:

    • Turbidimetric

    Reference Range:

    • 0.52–1.27 mg/L

    Reference Range:

    • 0.62–1.16 mg/L

    Life Extension’s Suggested Optimal Range:

    • <0.91 mg/L

    Life Extension’s Suggested Optimal Range:

    • <0.91 mg/L

    Liver Enzymes: Alanine Transaminase (ALT/SGPT), Alkaline Phosphatase, Aspartate Aminotransferase (AST/SGOT), Lactate Dehydrogenase (LDH)

    These liver enzymes are used to evaluate liver function. Both ALT and AST are abundant in the liver, and their levels increase with liver disease and sometimes with intense exercise (Giannini 2005). Personalized reference ranges are listed on laboratory results as they vary according to age and sex.

    Quest Diagnostics LabCorp

    Test Method:

    • Spectrophotometry (SP)

    Test Method:

    • Turbidimetric

    Reference Range:

    • ALT/SGPT:
      Women:
      6–29 U/L (≥20y)
      Men:
      9–46 (≥20y)
    • AST/SGOT:
      Women:
      10–30 U/L (20–44y)
      10–35 U/L (≥45y)
      Men:
      10–40 U/L (20–49y)
      10-35 U/L (≥50y)
    • LDH:
      Women:
      100–200 U/L (18–49y)
      120–250 U/L (>49y)
      Men:
      100–220 U/L (18–49y)
      120–250 U/L (>49 y)

    Reference Range:

    • ALT/SGPT: 0–44 IU/L
    • AST/SGOT: 0–40 IU/L
    • LDH:
      Women: 119-226 IU/L (>17y)
      Men: 121-224 IU/L (>17y)

    Total Serum Protein

    Total proteins are decreased in people with abnormal loss from the digestive tract, malnutrition, certain kidney diseases, or poor liver function.

    Quest Diagnostics LabCorp

    Test Method:

    • Spectrophotometry (SP)

    Test Method:

    • Colorimetric

    Reference Range:

    • 6.1–8.1 g/dL

    Reference Range:

    • 6.0–8.5 g/dL

    12 Thyroid Health

    Thyroid-Stimulating Hormone (TSH) (serum)

    Thyroid stimulating hormone (TSH) is produced and secreted by the pituitary gland and stimulates the thyroid to make T3 and T4. Increased TSH levels may indicate low thyroid function (Chakera 2012). When TSH is low, it may indicate high thyroid function (Girgis 2011). TSH is used as a first-line screening tool to assess thyroid disease; however, by itself it is insufficient, and needs to be evaluated in conjunction with other thyroid markers such as T3, T4, thyroid antibodies, and other tests (Iddah 2013; Ross 1989; Toft 2003).

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • 0.40–4.50 µIU/L

    Reference Range:

    • 0.45–4.50 µIU/mL

    Life Extension’s Suggested Optimal Range:

    • 1-2 µIU/mL (if >2 may indicate early thyroid concerns – best to monitor thyroid hormones)

    Life Extension’s Suggested Optimal Range:

    • 1-2 µIU/mL (if > 2 may indicate early thyroid concerns)

    Free Tri-Iodothyronine (T3) (serum)

    This test measures the amount of T3 available to the tissues, or free T3 (Sapin 2003). Many doctors believe that evaluating levels of free T3 is the best indicator of thyroid function (DeGroot 2016). Hypothyroidism is a condition where T3 blood levels are often (but not always) low (Koulouri 2013). This causes cellular dysfunction and metabolic disturbances (Sanyal 2016; Harper 2008; Brent 2012). Symptoms may include weight gain, constipation, dry skin, and hair loss. Hypothyroidism can lead to the development of chronic diseases, such as heart disease, and increases the risk of diabetes (Gronich 2015; Rodondi 2010; Chaker 2016).

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • 2.3–4.2 pg/mL

    Reference Range:

    • 2.0–4.4 pg/mL

    Life Extension’s Suggested Optimal Range:

    • 3.26–4.2 pg/mL

    Life Extension’s Suggested Optimal Range:

    • 3.4–4.2 pg/mL

    Total Thyroxine (T4) (serum)

    T4 is a hormone produced and secreted by the thyroid gland. At the tissue level, T4 is converted into the more active form of T3. For this reason, T4 is considered a measurement of total production of thyroid hormone. T4 blood levels are low in hypothyroidism, but may also be in the normal range (Chakera 2012). This causes cellular dysfunction and metabolic breakdown. Symptoms of hypothyroidism may include weight gain, constipation, dry skin, and hair loss. Low T4 levels may even lead to the development of chronic diseases such as heart disease and diabetes. T4 blood levels are elevated in hyperthyroidism, but may also be in the normal range or even low (Obuobie 2003; Santos Palacios 2012; Nygaard 2008). Symptoms of hyperthyroidism may include anxiety, insomnia, an increased heart rate, and bowel discomfort.

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • Women: 5.1–11.9 µg/dL
    • Men: 4.9–10.5 µg/dL

    Reference Range:

    • 4.5–12 µg/dL

    Life Extension’s Suggested Optimal Range:

    • N/A (It is most important to evaluate total T4 in the context of free thyroid hormones; especially Free T3 )

    Life Extension’s Suggested Optimal Range:

    • Male: 8.5–10.5 µg/dL
    • Female: 9–11 µg/dL (<60y); 8.5-10.7 µg/dL (>60y)

    Free T4 (serum)

    Proteins bind to T4 and carry it throughout the bloodstream. Once in the tissues, T4 is released from the proteins and free to convert into the more active form called T3. For this reason, many doctors believe that measuring free T4 is a good test for thyroid hormone production (Li 2014).

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • 0.8–1.8 ng/dL

    Reference Range:

    • 0.82–1.77 ng/dL

    Life Extension’s Suggested Optimal Range:

    • Top 2/3 of range (1.13–1.8 ng/dL)

    Life Extension’s Suggested Optimal Range:

    • Upper 3 rd of range (1.46–1.77 ng/dL)

    13 Inflammation

    C-Reactive Protein, high sensitivity (serum or plasma)

    The high-sensitivity C-reactive protein (hs-CRP) blood test measures the level of systemic inflammation. Uncontrolled systemic inflammation places you at risk for many degenerative diseases such as heart disease, stroke, and even increased cancer risk.

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoturbidimetric

    Test Method:

    • Immunochemiluminometric assay (ICMA)

    Reference Range:

    • <1.0 mg/L (low cardiovascular risk)
    • 1.0–3.0 mg/L (average cardiovascular risk)
    • >3.0 (high cardiovascular risk)

    Reference Range:

    • <1.0 mg/L (low cardiovascular risk)
    • 1.0–3.0 mg/L (average cardiovascular risk)
    • >3.0 (high cardiovascular risk)

    Life Extension’s Suggested Optimal Range:

    • <1.0 mg/L (lower is generally better)

    Life Extension’s Suggested Optimal Range:

    • <1.0 mg/L (lower is generally better)

    Generally, hs-CRP levels below 1 mg/L are considered low risk. However, it has also been suggested that “lower is better” when it comes to hs-CRP levels in the context of chronic disease risk. More clinical trial data are needed to determine whether people who already have relatively low hs-CRP levels (eg, around 1 mg/L) can benefit from treatment to further lower their hs-CRP levels.

    Interleukin-6 (IL-6) (serum)

    This test is used to identify elevated levels of interleukin-6 (IL-6). Elevated IL-6 serum or plasma levels may occur in sepsis, autoimmune diseases, lymphomas, HIV/AIDS, alcoholic liver disease, cancer progression, Alzheimer disease, and in concert with infections or transplant rejection. Elevated levels of IL-6 may be associated with an increased risk of heart attack or stroke (Kanda 2004; Cojocaru 2009). It is a good idea to test values of IL-6 with other cytokines such as IL-1 beta, IL-8, and TNF-alpha.

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence Immunoassay (ECLIA)

    Reference Range:

    • <5.00 pg/mL

    Reference Range:

    • 0.15.5 pg/mL

    Interleukin-8 (IL-8) (serum)

    This test is used to identify elevated levels of IL-8. Elevated IL-8 levels are observed in psoriasis, rheumatoid arthritis, chronic polyarthritis, cancer progression, and hepatitis C. It is a good idea to test measures of IL-8 with other cytokines such as IL-6, IL-1 beta, and TNF-alpha.

    Quest Diagnostics LabCorp

    Test Method:

    • Enzyme Immunoassay (EIA)

    Test Method:

    • Enzyme-linked immunosorbent assay (ELISA)

    Reference Range:

    • Up to 35.0 pg/mL

    Reference Range:

    • 0.0–66.1 pg/mL

    Tumor Necrosis Factor-alpha (TNF-alpha) (serum)

    This test is used to identify elevated levels of tumor necrosis factor-alpha. TNF-alpha levels may be elevated in sepsis, cachexia, HIV/AIDS, hepatitis C, transplant rejection, and various infectious and autoimmune diseases. It is a good idea to test measures of TNF-alpha with other cytokines such as IL-6, IL-8, and IL-1 beta.

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Enzyme-linked immunosorbent assay (ELISA)

    Reference Range:

    • 0.56–1.40 pg/mL

    Reference Range:

    • 0.0–2.2 pg/mL

    14 Men’s Health Concerns

    Testosterone (Total) (serum)

    Testosterone is a steroid hormone from the androgen group primarily secreted in the testes of males and the ovaries of females with small amounts also secreted by the adrenal glands (Burger 2002; Wood 2012).

    Testosterone is a key anabolic steroid responsible for directing metabolism and tissue repair and regeneration (Demling 2005; Wu 2014; Yu 2014). In men, testosterone also plays a key role in the development of male reproductive tissues as well as promoting secondary sexual characteristics such as increased muscle and bone mass and hair growth.

    In addition, testosterone is essential for overall health and wellness. Recent research has revealed the association between low testosterone and many age-related diseases. Conditions such as heart disease, osteoporosis, diabetes, and low libido are now thought to be attributed to what doctors call “low T” (Stanworth 2008; Rivas 2014; Huo 2016).

    On average, an adult male has about 10 times more testosterone in the circulation than an adult female (Gentil 2016). However, women are far more sensitive to testosterone than men. Women with low testosterone may be more at risk for bone disease, dysfunction of the blood vessels, heart disease, muscle wasting, tiredness, and loss of libido (Lorenz 2017; Bolour 2005; Kaczmarek 2003; Rohr 2002; Rech 2016; Burger 2006; Bachmann 2006).

    Quest Diagnostics LabCorp

    Test Method:

    • Chromatography-Mass Spectrometry

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • 250–1,100 ng/dL

    Reference Range:

    • 264–916 ng/dL (>18y)

    Life Extension’s Suggested Optimal Range:

    • 700–1,100 ng/dL

    Life Extension’s Suggested Optimal Range:

    • 600–900 ng/dL

    Free Testosterone (serum)

    Free testosterone is the biologically active form of this hormone measured in the blood.

    Quest Diagnostics LabCorp

    Test Method:

    • Equilibrium dialysis

    Test Method:

    • Enzyme immunoassay (EIA)

    Reference Range:

    • 35–155 pg/mL (18–69y)

    Reference Range:

    • 9.3–26.5 pg/mL (20–29y)

    Life Extension’s Suggested Optimal Range:

    • 115–155 pg/mL

    Life Extension’s Suggested Optimal Range:

    • 15–25 pg/mL

    Dihydrotestosterone (DHT) (serum or plasma, frozen)

    Dihydrotestosterone (DHT) is a potent form of testosterone required for male sexual development (Roth 2011; Hiort 2013). In adults, DHT is the primary androgen in the prostate and in hair follicles (Anitha 2009). DHT levels are higher in men with male-pattern baldness and prostate dysfunction (Dhingra 2011; Wright 2010). Remember, women with higher levels of DHT can also lose their hair (Urysiak-Czubatka 2014).

    Additionally, men and women on testosterone therapy should always check their testosterone blood level to make sure that it stays within an optimal range.

    Quest Diagnostics LabCorp

    Test Method:

    • Chromatography-Mass spectrometry

    Test Method:

    • High-performance liquid chromatography-mass spectrometry (HPLC-MS)

    Reference Range:

    • 12–65 ng/dL

    Reference Range:

    • 30–85 ng/dL

    Life Extension’s Suggested Optimal Range:

    • 30–50 ng/dL

    Life Extension’s Suggested Optimal Range:

    • 30–50 ng/dL

    Pregnenolone (serum or plasma, frozen)

    Pregnenolone is sometimes called “the mother of all hormones.” All other steroids including testosterone and estrogens are derived from this important hormone (Velarde 2014). For this reason, optimal blood levels of pregnenolone are critical for a healthy hormone balance. Pregnenolone is also important for proper brain development, cognition, memory, and mood (Ducharme 2010; Mellon 2007; Brown 2014; Ritsner 2010). These dramatic effects on the brain explain why pregnenolone is known as a neuro-active steroid.

    Quest Diagnostics LabCorp

    Test Method:

    · Chromatography-Mass spectrometry

    Test Method:

    · Liquid chromatography-tandem mass spectrometry (LC/MS-MS)

    Reference Range:

    • 22–237 ng/dL

    Reference Range:

    • <151 ng/dL

    Life Extension’s Suggested Optimal Range:

    • Top 1/3 of range (165–237 ng/dL)

    Life Extension’s Suggested Optimal Range:

    • 125–175 ng/dL

    Sex Hormone-Binding Globulin (SHBG) (serum)

    Testosterone and estradiol circulate in the bloodstream, bound mostly to sex hormone-binding globulin (SHBG) and to some degree other proteins. Only a small fraction of the sex hormones are unbound, or "free," and thus biologically active and able to activate their receptors (Holst 2004; Rosner 1991; Hammond 2016).

    SHBG levels should not be too low or too high. SHBG helps protect androgens like testosterone from being metabolized rapidly by the liver or excreted in the urine by the kidneys. If SHBG levels are too low, then testosterone will be metabolized and/or excreted too quickly and essentially wasted. If SHBG is too high, it decreases the active form of the hormone available to the tissues by binding too much of it up. Thus, bioavailability of sex hormones is influenced by the level of SHBG (Laurent 2016). High levels of insulin decrease SHBG level (Strain 1994). On the other hand, thyroid hormone and estrogen increase it (Serin 2001; Kalme 1999; Selva 2009).

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • 10–50 nmol/L (18–55)
    • 22–77 nmol/L (<55)

    Reference Range:

    • 16.5–55.9 nmol/L (20–49)
    • 19.3–76.4 nmol/L (<49)

    Life Extension’s Suggested Optimal Range:

    • ~30–40 nmol/L

    Life Extension’s Suggested Optimal Range:

    • ~30–40 nmol/L

    Estradiol (E2) (serum)

    Estradiol (E2) is the predominant sex hormone present in females and is also found at lower levels in men (Wise 2009; Schulster 2016). In men, high levels of estradiol are associated with abdominal fat, enlargement of the prostate, and cardiovascular risk. Also, low levels below 18 are associated with increased risk of fracture (Amin 2006).

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • ≤ 39 pg/mL

    Reference Range:

    • 7.6–42.6 pg/mL

    Life Extension’s Suggested Optimal Range:

    • 20–40 pg/mL

    Life Extension’s Suggested Optimal Range:

    • 20–40 pg/mL

    Total Estrogens (serum or plasma)

    Total estrogen is a measurement of overall estrogen status. Estrogens are important regulators of reproductive and non-reproductive organs in men (Cooke 2017). They are involved in sexual development, lipid metabolism (Kula 2005), bone health (Vandenput 2009), and regulate body weight and adiposity (Rubinow 2017), immunity (Ercan 2017) and cardiovascular health (Sudhir 1999). The total estrogen test does not break down the individual estrogens but looks at the total body burden of estrogens and can even include exogenous estrogens such as phytoestrogens and xenoestrogens from the environment.

    Quest Diagnostics LabCorp

    Test Method:

    • Enzyme-linked immunoassay (ELISA)

    Test Method:

    • Enzyme-linked immunoassay (ELISA)

    Reference Range:

    • ≤404 pg/mL

    Reference Range:

    • 56–213 pg/mL

    Prostate-Specific Antigen (PSA) (serum)

    Prostate specific antigen (PSA) is produced exclusively by cells of the prostate gland (Lilja 1988; Sp 2013). Used in conjunction with the digital rectal examination, PSA is a useful screening test for benign prostatic hyperplasia (BPH) and prostate cancer. The real value of the PSA test is looking at trends over time versus a single PSA reading.

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • 0.0–4.0 ng/dL

    Reference Range:

    • 0.0–4.0 ng/mL

    Life Extension’s Suggested Optimal Range:

    • >1–2 ng/mL may indicate
      very early-stage
      cancer
    • < 1.0 ng/mL

    Life Extension’s Suggested Optimal Range:

    • >1–2 ng/mL may indicate
      very early-stage
      cancer
    • < 1.0 ng/mL

    Alpha-fetoprotein (AFP) (serum)

    Alpha-fetoprotein (a-FP, AFP) has several applications, the most important being in the management of testicular cancer.

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • <6.1 ng/dL

    Reference Range:

    • 0.0–8.3 ng/mL

    Refer to Life Extension’s Male Hormone Restoration protocol for additional information about the benefits of these and other tests to overall health.

    15 Women’s Health Concerns

    Pregnenolone (serum or plasma, frozen)

    Pregnenolone is sometimes called “the mother of all hormones.” All other steroids including testosterone and estrogens are derived from this important hormone (Velarde 2014).

    Quest Diagnostics LabCorp

    Test Method:

    • Chromatography-Mass spectrometry

    Test Method:

    • Liquid chromatography-tandem mass spectrometry (LC/MS-MS)

    Reference Range:

    • 22–237 ng/dL

    Reference Range:

    • <151 ng/dL

    Life Extension’s Suggested Optimal Range:

    • Top 1/3 of range (165-237 ng/dL)

    Life Extension’s Suggested Optimal Range:

    • 130–180 ng/dL

    Estradiol (E2) (serum)

    Estradiol (E2) is the predominant sex hormone present in women and is also found at lower levels in men (Wise 2009; Schulster 2016). It represents the most important estrogen, functionally, in humans (Chai 2014; Vermeulen 2002). E2 not only impacts reproductive and sexual functioning, but also affects other systems including bone health, heart health, the nervous system, and metabolism (Cui 2013; Bunt 1990).

    E2 is the most active of all three estrogens commonly measured in a clinical setting (Wise 2009; Yang 2017). For women, it is important to compare the relationship between E2 and progesterone in evaluating menopausal symptoms such as hot flashes, mood disorders, and aging skin.

    In both men and women, low levels of E2 are associated with osteoporosis (Vermeulen 2002; Shi 2017; Klaiber 1982; Carlsen 2000; Ettinger 1993; Quigley 1987).

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • Follicular: 30–144 pg/mL
    • Mid-cycle: 64–357 pg/mL
    • Luteal: 56–214 pg/mL

    Postmenopausal:≤31 pg/mL (no hormone replacement therapy [HRT])

    Reference Range:

    • Follicular: 12.5–166.0 pg/mL
    • Ovulation: 85.8–498 pg/mL
    • Luteal: 43.8–211.0 pg/mL

    Postmenopausal: <6.0–54.7 pg/mL

    Life Extension’s Suggested Optimal Range:

    • Symptom control:
      ~ 25–40 pg/mL
    • Bone Density Support:
      ~ 60–80 pg/mL

    Life Extension’s Suggested Optimal Range:

    • Lowest levels shown to ameliorate symptoms: 30–50 pg/mL
    • With typical Bi-est: 80–100 pg/mL
    • Restoration of menstrual cycle (around day 21): 90–211 pg/mL

    Total Estrogens (serum or plasma)

    Total estrogen is a measure of overall estrogen status. In addition to their role in reproduction, estrogens affect several organs in the body. They are critical for the functioning of the nervous system, cardiovascular health (Navarro-Pardo 2017), and are involved in cognitive functioning (Sherwin 2003), metabolic pathways, muscle strength, the responses to injury and inflammation (Horstman 2012), and in maintaining the health of the urinary tract (Robinson 2003). Clinically estrogens are important in evaluating symptoms of menopause, cardiovascular risk, and bone health in aging women (Baker 2003; Wharton 2012; Riggs 2000). The total estrogen test does not break down the individual estrogens but looks at the total body burden of estrogens and can even include exogenous estrogens such as phytoestrogens and xenoestrogens from the environment.

    Quest Diagnostics LabCorp

    Test Method:

    • Enzyme-linked immunosorbent assay (ELISA)

    Test Method:

    • Enzyme-linked immunosorbent assay (ELISA)

    Reference Range:

    • 40–244 pg/mL (postmenopausal)

    Reference Range:

    • 40–244 pg/mL (postmenopausal)

    Progesterone (serum)

    In both men and women, progesterone balances and offsets the powerful effects of estrogens. Some of the most common concerns of aging that women have include weight gain, insomnia, anxiety, depression, and migraines. For other women, even more debilitating conditions such as cancer, uterine fibroids, ovarian cysts, and osteoporosis may affect them at various stages of their lives.

    As men age, complaints of weight gain, loss of libido, and prostate enlargement top their list of health concerns. Many physicians and scientists are becoming more aware of a common link between these conditions and an imbalance between two sex hormones: progesterone and estrogen.

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • Follicular: <1 ng/mL
    • Luteal: 2.6–21.5 ng/mL

    Postmenopausal: <0.5 ng/mL

    Reference Range:

    • Follicular: 0.1–0.9 ng/mL
    • Ovulation: 0.1–12.0 ng/mL
    • Luteal: 1.8–23.9 ng/mL

    Postmenopausal: 0.0–0.1 ng/mL

    Life Extension’s Suggested Optimal Range:

    • 10–21.5 ng/dL (premenopause at day 21)
    • 2–6 or even higher (BHRT only)

    Life Extension’s Suggested Optimal Range:

    • 15–23 ng/mL (premenopause at day 21)
    • 2–6 ng/mL (menopause)

    Testosterone (Total) (serum)

    Testosterone is a steroid hormone from the androgen group primarily secreted in the testes of males and the ovaries of females with small amounts also secreted by the adrenal glands (Burger 2002; Wood 2012). On average, an adult male has about 10 times more testosterone in the circulation than an adult female (Gentil 2016). However, women are far more sensitive to testosterone than men. Women with low testosterone may be more at risk for bone disease, dysfunction of the blood vessels, heart disease, muscle wasting, tiredness, and loss of libido (Lorenz 2017; Bolour 2005; Kaczmarek 2003; Rohr 2002; Rech 2016; Burger 2006; Bachmann 2006).

    Quest Diagnostics LabCorp

    Test Method:

    • Liquid Chromatography with Tandem Mass spectrometry (LC/MS/MS)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • 2–45 ng/dL (≥18y)

    Reference Range:

    • 13–71 ng/dL (20-30)

    Life Extension’s Suggested Optimal Range:

    • 28–40 ng/dL

    Life Extension’s Suggested Optimal Range:

    • 35–60 ng/dL

    Free Testosterone (serum)

    Free testosterone is the biologically active form of this hormone measured in the blood.

    Quest Diagnostics LabCorp

    Test Method:

    • Equilibrium dialysis

    Test Method:

    • Enzyme immunoassay (EIA)

    Reference Range:

    • 0.1–6.54 pg/mL (18-69y)

    Reference Range:

    • 0-4.2 (>19y)

    Life Extension’s Suggested Optimal Range:

    • 3.25–6.4 pg/mL

    Life Extension’s Suggested Optimal Range:

    • 2.1–4.2 pg/mL

    Sex Hormone-Binding Globulin (SHBG) (serum)

    Testosterone and estradiol circulate in the bloodstream, bound mostly to sex hormone-binding globulin (SHBG) and to some degree other proteins. Only a small fraction of the sex hormones is unbound, or "free," and thus biologically active and able to activate their receptors (Holst 2004; Rosner 1991; Hammond 2016).

    SHBG levels should not be too low or too high. SHBG helps protect androgens like testosterone from being metabolized rapidly by the liver or excreted in the urine by the kidneys. If SHBG levels are too low, then testosterone will be metabolized and/or excreted too quickly and essentially wasted. If SHBG is too high, it decreases the active form of the hormone available to the tissues by binding too much of it up. Thus, bioavailability of sex hormones is influenced by the level of SHBG (Laurent 2016). High levels of insulin decrease SHBG level (Strain 1994). On the other hand, thyroid hormone and estrogen increase it (Serin 2001; Kalme 1999; Selva 2009).

    Quest Diagnostics LabCorp

    Test Method:

    • Immunoassay (IA)

    Test Method:

    • Electrochemiluminescence immunoassay (ECLIA)

    Reference Range:

    • 17–124 nmol/L (18-55y)
    • 14–73 nmol/L (<55y)

    Reference Range:

    • 24.6–122 nmol/L (20-49y)
    • 17.3–125 nmol/L (<49y)

    Life Extension’s Suggested Optimal Range:

    • ~60–80 nmol/L

    Life Extension’s Suggested Optimal Range:

    • ~60–80 nmol/L

    Refer to Life Extension’s Female Hormone Restoration protocol for additional information about the benefits of these and other tests to overall health.

    2026

    • Mar: Comprehensive update & review

    2025

    • Jan: Updated section on C-reactive protein, high sensitivity (serum or plasm) in Inflammation

    2023

    • Apr: Updated Life Extension’s optimal range for fasting insulin in Blood Sugar
    • Jan: Added section on sodium to Chemistry Panel and Complete Blood Count: The Most Common Blood Test

    2021

    • Jul: Updated section on total testosterone in Women's Health Concerns

    2018

    • Mar: Comprehensive update & review

    Disclaimer and Safety Information

    This information (and any accompanying material) is not intended to replace the attention or advice of a physician or other qualified health care professional. Anyone who wishes to embark on any dietary, drug, exercise, or other lifestyle change intended to prevent or treat a specific disease or condition should first consult with and seek clearance from a physician or other qualified health care professional. Pregnant women in particular should seek the advice of a physician before using any protocol listed on this website. The protocols described on this website are for adults only, unless otherwise specified. Product labels may contain important safety information and the most recent product information provided by the product manufacturers should be carefully reviewed prior to use to verify the dose, administration, and contraindications. National, state, and local laws may vary regarding the use and application of many of the therapies discussed. The reader assumes the risk of any injuries. The authors and publishers, their affiliates and assigns are not liable for any injury and/or damage to persons arising from this protocol and expressly disclaim responsibility for any adverse effects resulting from the use of the information contained herein.

    The protocols raise many issues that are subject to change as new data emerge. None of our suggested protocol regimens can guarantee health benefits. Life Extension has not performed independent verification of the data contained in the referenced materials, and expressly disclaims responsibility for any error in the literature.

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