We have no data to show that testosterone helps to prevent heart attacks in older men. In an effort to find out if taking testosterone could help to prevent heart attacks, doctors gave injections of testosterone to 45 men and placebo to 43 men for 40 weeks (Clin Endocrinol (Oxf), Jan 2016;84(1):55-62). Both groups of men:
• were 35 to 70 years old,
• were at high risk for heart attacks because they had diabetes, and
• had low testosterone.
Those treated with testosterone showed a reduction in the cardiac biomarker NT-proBNP, but no reduction in another biomarker, hs-cTnT.
What are Cardiac Biomarkers?
Cardiac biomarkers are chemicals that are located inside heart muscle cells. When heart muscle cells are damaged, the biomarkers are released from inside the cells into the bloodstream. N Terminal-pro B-type natriuretic peptide (NT-proBNP) and High-sensitivity cardiac troponin T (hs-cTnT) are released from swollen and damaged heart muscle. Both can be used to determine if a person is at high risk for a heart attack as well as if a person is having a heart attack. However, since this study showed reduction in one biomarker but not in the other, we still have no good evidence that testosterone helps to prevent heart attacks.
Testosterone May Increase Heart Attack Risk
In an earlier study, more than 1,000 men with low testosterone and no heart disease screened by coronary angiography were treated with testosterone. Those treated with testosterone had a significant increase in strokes and heart attacks over the next three years, compared to the control group (JAMA, November 6, 2013;310(17):1829-1836). Taking testosterone can thicken blood, which would increase risk for heart attacks or strokes. Taking testosterone can also enlarge male breasts and cause acne.
Functions of Testosterone
Testosterone is a hormone produced by the bodies of both men and women, but at much higher levels in men. It helps build muscles, lowers voice pitch, increases penile or clitoral size, strengthens bones and increases libido. Men with low levels of testosterone can suffer low sexual drive, erectile problems, decreased strength and osteoporosis. We have no good data to show that the low testosterone causes depression, excessive tiredness, problems concentrating, insomnia or irritability, even though these symptoms are often found in men with low testosterone levels.
Blood levels of testosterone start to drop after the age of 30. Obesity damages testicles to lower testosterone level. Obesity also causes diabetes, so most men with diabetes have lower than normal testosterone levels (Diabetes Care, 2011;34(7):1669-1675).
Do Not Take Testosterone If:
• You have symptoms of low energy or depression but your testosterone is normal.
• You have prostate cancer. Testosterone therapy does not appear to cause prostate cancer, but it can make it grow and spread through your body. It is controversial whether patients who have been treated for prostate cancer should take testosterone.
• You have severe urinary tract symptoms caused by an enlarged prostate or you have a lump on your prostate gland found during a digital rectal exam.
• You want to have children. Taking testosterone can lower sperm count to decrease fertility. The sperm usually disappear after 10 weeks of testosterone.
• You have polycythemia (too many red blood cells). Testosterone increases red blood cell production.
• You are at increased risk for forming clots. Testosterone raises red blood cell counts to thicken the blood and increase heart attack risk.
• You have sleep apnea. Testosterone can increase risk for stopping breathing during sleep in people who already have that condition.
• You are obese. Losing weight may cure your symptoms that were caused by obesity or diabetes. Taking testosterone cures neither diabetes nor obesity and does not change your high risk for a heart attack.
If You Do Take Testosterone
You need frequent blood tests for testosterone and PSA levels and a digital-rectal exam to check for prostate cancer, and hemoglobin blood tests to make sure that your blood is not becoming so thick that it can cause a heart attack. If the symptom you are treating does not get better in two months, you should stop taking testosterone as it is not working and it may be harming you.