|A Comprehensive Guide to Preventative Blood Testing|
By Penny Baron
C-Reactive Protein (CRP) and the Cardio CRP Test
While still present, these risk factors continue to facilitate the attraction and accumulation of inflammatory cells—macrophages, mast cells, and activated T-lymphocytes—within the atherosclerotic plaque. Disruption of this plaque, caused by chronic inflammation, may cause a heart attack as oxygen-deprived blood vessels become clogged with pieces of dislodged plaque material.
C-reactive protein is a very sensitive marker of systemic inflammation, and has emerged as a powerful predictor of coronary heart disease21 and other cardiovascular diseases.
The highly sensitive cardio CRP test is able to measure the presence of C-reactive protein in the blood, even at very early stages of vascular disease, allowing for appropriate intervention with diet, supplements, or anti-inflammatory therapy.
Elevated levels of C-reactive protein have also been found to be associated with risk of developing diabetes Type II,22 loss of cognitive ability in seemingly healthy people,23 Alzheimer’s disease, and depression in the elderly. Furthermore, risk factors for atherosclerosis and heart disease, such as smoking and high blood pressure, elevate blood levels of C-reactive protein that can be detected by the cardio CRP test.24
PSA (prostate specific antigen); free and complexed
PSA is normally found at million-fold lower concentrations in the serum than in the seminal fluid. In seminal fluid, PSA predominantly exists in the “free” (uncomplexed) state; in serum, it is generally found bound to inhibitors. Risk of prostate cancer may be assessed by determining absolute amounts of total PSA or by calculating the percent of free PSA compared to total PSA (complexed plus uncomplexed). A study in the New England Journal of Medicine found that 25% of patients with normal digital rectal exams (DRE) and total PSA levels of 4.0–10.0 ng/ml had prostate cancer.25 In the same study group, researchers calculated that risk of prostate cancer increased with decreases in the percentage of free PSA in the serum. In other words, as the ratio of complexed to free PSA increased (concomitant with total increased levels of PSA), risk of prostate cancer increased dramatically.
It should be noted that elevated levels of PSA may not necessarily signal prostate cancer, and prostate cancer may not always be accompanied by expression of PSA. Levels may be elevated in the presence of a urinary tract infection and an inflamed prostate.
In another study recently published in the New England Journal of Medicine, investigators recommended lowering the PSA cutoff from 4.1 ng/ml (the threshold at which biopsy is currently recommended). At the current threshold, it was determined that “82 percent of cancers in younger men and 65 percent of cancers in older men would be missed.”26 But levels below the currently recognized cutoff of 4.1 ng/ml may not distinguish between prostate cancer and benign prostate disease. New tests looking at PSA precursor (proPSA) alongside PSA may aid in improving diagnosis. Clinical trials are currently under way.27
Systemic inflammation and tests for proinflammatory cytokines TNF-a, IL-6, IL-1b and IL-8
Cytokines are cellular growth factors that are synthesized by nearly every cell of the body and are generally produced only in response to “stress.” Secreted primarily from leukocytes (white blood cells), cytokines regulate the hosts’ response to infection, immune responses, inflammation, and trauma. Cytokines may be either proinflammatory (worsen disease) or anti-inflammatory (reduce inflammation and promote healing). Some studies suggest that susceptibility to disease may result from an imbalance between pro- and anti-inflammatory cytokines.29
There is also mounting evidence that depression may directly stimulate the production of proinflammatory (primarily IL-6) cytokines or indirectly stimulate production by down-regulating the cellular immune response (i.e., prolonged infection and delayed healing fuel sustained cytokine release).30
The pro-inflammatory cytokine panel detects abnormally high levels of the most dangerous inflammatory cytokines in the blood: tumor necrosis factor-a (TNF-a), interleukin-6 (IL-6), interleukin-1 beta (IL-1b), and interleukin-8 (IL-8).