The 10 Most Important Blood TestsMay 2006
By Penny Baron
Dehydroepiandrosterone (DHEA), a hormone produced by the adrenal glands, is a precursor to the sex hormones estrogen and testosterone. Blood levels of DHEA peak in one’s twenties and then decline dramatically with age, decreasing to 20-30% of peak youthful levels between the ages of 70 and 80. DHEA is frequently referred to as an “anti-aging” hormone.
Recently, researchers in Turkey found that DHEA levels were significantly lower in men with symptoms associated with aging, including erectile dysfunction.9 Healthy levels of DHEA may support immune function, bone density, mood, libido, and healthy body composition.10
Elevated levels of DHEA may indicate congenital adrenal hyperplasia, a group of disorders that result from the impaired ability of the adrenal glands to produce glucocorticoids.11-12
Supplementation with DHEA increases immunological function, improves bone mineral density, increases sexual libido in women, reduces abdominal fat, protects the brain following nerve injury, and helps prevent diabetes, cancer, and heart disease.10
Emerging research suggests that DHEA may have antidepressant effects. In a report in the January 2006 issue of the American Journal of Psychiatry, investigators found that in HIV-infected men and women, supplementation with DHEA was superior to placebo in treating non-major depression (with a response rate of 62% vs. 33%, retrospectively).13
In another study from the National Institute of Mental Health, investigators found that DHEA significantly improved midlife-onset major and minor depression in men and women aged 45 to 65 years old.14
Furthermore, a recently published study from Israel demonstrated that DHEA administration decreased self-administration of cocaine in rats, suggesting a potential for DHEA in reducing cravings and supporting recovery from addiction.15
In a recent study published in the Journal of Investigative Dermatology, scientists demonstrated that DHEA levels were significantly lower in elderly persons predisposed to chronic wound conditions, such as venous ulcers, and that administration of DHEA accelerated wound healing in aging mice. This led the research team to suggest that DHEA supplementation may be a safe, effective strategy to improve wound healing in the elderly.16
Natural therapies may help to optimize DHEA levels. You may wish to discuss with your doctor the use of pregnenolone or DHEA. Those with estrogen-related cancers such as breast or prostate cancer should not use DHEA.
5. Prostate-Specific Antigen (PSA) (Men Only)
Prostate-specific antigen (PSA) is a protein manufactured by the prostate gland in men. Elevated levels may suggest an enlarged prostate, prostate inflammation, or prostate cancer. PSA levels may also be used to monitor the efficacy of therapeutic regimens for prostate conditions.
Elevated levels of PSA may not necessarily signal prostate cancer, and prostate cancer may not always be accompanied by expression of PSA. Levels can be elevated in the presence of a urinary tract infection or an inflamed prostate. A PSA level over 2.5 ng/mL, or a PSA doubling time (the time required for PSA value to double) of less than 12 years, may be a cause for concern.
The American Cancer Society recommends annual PSA testing for men beginning at age 50. Men who are at high risk should begin PSA testing at age 40-45. PSA levels increase with age, even in the absence of prostate abnormalities.17
More than 15% of men with PSA values between 2.6 and 4.0 ng/mL who are 40 years or older have prostate cancer, according to a prostate cancer screening study published in 2005 in the Journal of Urology.18
According to a study published in the Journal of the American Medical Association, 25% of patients with normal digital rectal exams and total PSA levels of 4.0-10.0 ng/mL have prostate cancer.19 In a later study published in the New England Journal of Medicine, investigators recommended that “lowering the threshold for biopsy from 4.1 to 2.6 ng per milliliter in men younger than 60 years would double the cancer-detection rate from 18 percent to 36 percent.”20 It should be noted that levels below the currently recognized cutoff of 4.1 ng/mL may not distinguish between prostate cancer and benign prostate disease.
In a recently published study in the journal Urology, prostate cancer was detected in 22% of patients with PSA levels between 2.0 and 4.0 ng/mL, and most of those cancers biopsied were significant, leading researchers to conclude that an “important number of cancers could be detected in the PSA rangeof 2.0 to 4.0 ng/mL.”21 In another study, investigators in Spain detected significant cancers in some patients with a PSA range between 1.0 and 2.99 ng/mL. Although the risk of developing cancer for those in the low PSA range is small, the authors said, it is still relevant.22
A healthy Mediterranean-type diet may offer protection against prostate cancer and other diseases associated with aging. Natural therapies may also help support prostate health. You and your physician may wish to discuss the use of saw palmetto, beta-sitosterol, pygeum, and nettle root extracts. (See also “Beta-Sitosterol and the Aging Prostate Gland,” Life Extension, June 2005.)
The amino acid homocysteine is formed in the body during the metabolism of methionine. High homocysteine levels have been associated with increased risk of heart attack, bone fracture, and poor cognitive function.
Incremental increases in the level of homocysteine correlate with an increased risk for coronary artery disease. Data from the Physicians’ Health Study, which tracked 14,916 healthy male physicians with no previous history of heart disease, showed that highly elevated homocysteine levels were associated with a more than threefold increase in the risk of heart attack over a five-year period.23
Homocysteine has also become recognized as an independent risk factor for bone fractures. In a recent study of 1,267 men and women with an average age of 76, investigators in the Netherlands concluded that high homocysteine levels and low vitamin B12 concentrations were significantly associated with an increased risk for bone fracture.24 This mirrors data from two previous studies published in 2004 in the New England Journal of Medicine, in which elevated homocysteine levels were shown to be an important and independent risk factor for osteoporotic fractures, including hip fractures.25,26
Elevated homocysteine levels have recently been linked to other disorders. In three recent studies, investigators found an association between elevated homocysteine levels and age-related macular degeneration.27-29 In Japan, increased homocysteine levels were found to be associated with the presence of gallstones in middle-aged men. Investigators suggested that this association “may partly explain the reported high prevalence rate of coronary heart disease” in persons with gallstones.30
A study from the Netherlands has shown that among normal individuals aged 30-80, elevated homocysteine concentrations are associated with prolonged lower cognitive performance.31
Natural therapies may help to optimize homocysteine levels. You may wish to discuss with your doctor the use of vitamin B12, vitamin B6, folic acid, and trimethylglycine.