Cardiovascular Disease
Current clinical research suggests that sex hormones work in opposite ways in men and women to impact cardiovascular disease processes. Thus, while estrogen generally has a protective influence on cardiovascular health in women, high levels of this ‘female’ sex hormone in men are associated with an increased risk of angina, coronary artery disease, and myocardial infarction.7,8 Conversely, though testosterone may exert a detrimental influence on cardiovascular dynamics in women, it produces strong beneficial effects on an amazingly wide array of CVD risk factors in men.9
A variety of physiological mechanisms may explain the associations between testosterone imbalances and the pathogenesis of coronary disease, myocardial infarction, and stroke, in addition to testosterone’s ability to modulate lipid and glucose factors. Low testosterone is linked to higher levels of fibrinogen and plasminogen activator inhibitor, which play a crucial role in blood viscosity, plaque formation, and platelet aggregation. Experimental studies also show testosterone capable of triggering vasodilation of the arteries — a relaxant effect believed to have a beneficial impact on angina and other cardiovascular impairments.
Testosterone deficiency has been called the “primary event” initiating the synergistic process involving insulin resistance, diabetes, myocardial infarction and stroke. Testosterone levels independently predict the likelihood of developing diabetes, and restoring depleted levels has been shown to improve insulin resistance.
While early studies examining the specific relationship between testosterone and cardiovascular factors in men sometimes produced inconclusive results, many investigators now believe that these inconsistencies may have stemmed, in part, from the limitations of measuring total testosterone levels in blood, rather than the more clinically significant bioavailable fraction of testosterone. The bioavailable form of testosterone is more readily available to target tissues and organs in the body, and has been shown to display a stronger negative correlation with coronary artery disease parameters than total testosterone levels.
Clinical Studies
Testosterone Levels
Research studies have demonstrated that higher levels of testosterone conferred a protective ratio against atherosclerotic coronary artery disease (ASCAD) of greater than five-fold in men. Phillips, et al. reported an inverse correlation between free testosterone levels and both the degree of coronary artery disease and the various risk factors for myocardial infarction. Chronically low testosterone levels, they concluded, may actually precede — and thus in part precipitate — coronary artery disease and thrombosis in men.10
“A normal physiological level of testosterone may protect against the development of hyperlipidaemia, hyperinsulinism, hypertension, thrombophilic tendency, obesity and increased waist-hip ratio,” echoed British cardiologists in the Quarterly Journal of Medicine. “The decline of testosterone with age may partly explain the greater risk of CAD with advancing years.” They emphasize the importance of identifying young men with relative hypogonadism, who are at increased risk of premature CAD. These patients may only exhibit symptoms of fatigue and depression, while “the true diagnosis is unsuspected and undiagnosed.” 11 This recommendation is supported by a cross-sectional study of South African Indian men, which revealed lower testosterone levels in younger men with premature coronary artery disease. 12
