There’s been a recent concern about testosterone and heart disease. A study published in the New England Journal of Medicine in 2010 found an increased risk of heart disease in men over the age of 65 while taking testosterone; and a study published in PLOS One in 2014 found an increased risk of heart disease in men under the age of 65 while taking testosterone. These findings were unexpected, and run counter to the decades of research and hundreds of studies published on testosterone showing it to be beneficial to the cardiovascular system. So why the disparity now? Why were the results from these two recent studies so different from previous studies? There are 3 reasons for this:
Excess red blood cells: In some men, testosterone can stimulate the bone marrow to produce more red blood cells. While this is desirable for someone who is anemic, it is not desirable for someone possessing risk factors for heart disease including high cholesterol, high blood pressure, diabetes, smoking, excess weight, physical inactivity, and family history of early heart disease. Too many red blood cells—a condition known as erythrocytosis—can make the blood too viscous (thick) and potentially cause it to clump together and clot. Blood viscosity is measured by a routine lab test called hematocrit. Hematocrit measures the percentage of the volume of whole blood that is made up of red blood cells. Reference ranges vary slightly among laboratories, but in general, the full range is 40-54 percent. Unfortunately, in neither of the two studies cited above was hematocrit ever measured.
Excess estrogen: Testosterone therapy can increase a man’s level of estrogen. Women synthe-size estrogen in their ovaries. Since men lack this part of the female anatomy, they produce needed estrogen through a biochemical process involving an enzyme called aromatase that converts a small portion of their testosterone to estrogen. Optimal levels of estrogen have numerous health-promoting benefits, however, excess estrogen has been linked to an increased risk of heart disease (not to mention prostate disease). Reference ranges for estrogen (estradiol) vary slightly among laboratories, but in general, the full range is 0-56 pg/mL. Unfortunately, in neither of the two studies cited about was estrogen ever measured.
Excess testosterone: In the two studies cited above, the primary treatment was transdermal (topically-applied) testosterone. It is assumed that when testosterone is delivered to the body topically with creams, gels, or roll-on liquids, only 10 percent is absorbed. It is also assumed that when testosterone is delivered to the body topically, the standard venous blood test accurately reflects how much testosterone is getting to the tissues throughout the body. Under these assumptions, the FDA has approved daily dosages of topical testosterone that are 10 times higher (50-100 mg) than the daily amount healthy young men produce naturally in their testicles (5-10 mg). Unfortunately, both of these assumptions are wrong, and are causing millions of men to be overdosed from topical testosterone. This is because topical testosterone is transported primary by the lymphatic system and not the circulatory system.
Short of a direct determination via tissue biopsy, the way to indirectly determine the tissue level of testosterone is to measure the level in capillary blood from a specialized finger-prick test. Capillary blood is more representative of the amount of testosterone at the tissue level whereas venous blood is not. This is because venous blood measures the amount of testosterone being car-ried away from the tissues, and capillary blood measures the amount of testosterone being car-ried toward the tissues. In healthy young men, the level of testosterone in the venous blood is equivalent to the level of testosterone in capillary blood. However, in many patients that are using topical testosterone, the level of testosterone in the capillary blood exceeds that of venous blood by as much as 10-20 times. At these extreme levels, testosterone itself may increase the risk of heart disease.
When administered correctly, testosterone is very safe. The operative word is “correctly.” Testo-sterone therapy can be one of the most effective ways to reduce the signs of aging and regain more mental and physical vigor. Furthermore, numerous studies have shown that testosterone can help make men less vulnerable to heart disease, diabetes, Alzheimer’s, obesity, sarcopenia (loss of mus-cle), osteoporosis, depression, and even premature death. In short, testosterone can greatly improve a man's health and well-being. And when combined with proper diet and the right type of exercise, the synergistic effect can be quite profound.
Dr. Daniel Thomas, DO, MS is Medical Director of More T Clinics in Altamonte Springs. He is author of The Doctor’s Guide to Testosterone Therapy, and publisher of Healthy and Strong: The quarterly guide to living long and living well. In addition to a medical degree, he holds a Master of Science degree in Metabolic and Nutritional Medicine, and a post-Master’s Graduate Certificate in Metabolic Endocrinology, both from the University of South Florida College of Medicine.