Testosterone and Heart Attacks: Q&A
Does the research so far tip the balance one way or the other?
Experts disagree. "I think if you look at all the data in summary, there is not a clear trend towards increased risk of cardiovascular events -- stroke and heart attack, and early death -- or a clear trend toward blood clot formation [with testosterone use]," Anawalt says.
In June, the FDA added a general warning label to testosterone products, describing the risk of blood clots in the veins. The blood clot warning is not related to the FDA's ongoing evaluation of the possible link between testosterone and heart attack, according to the agency.
Greenland says the studies, overall, do show a risk. "More studies have found an association than have not," he says.
Experts do agree that, if needed, testosterone therapy can be helpful.
How is low testosterone defined, and how many men have it?
About 5 million American men have low testosterone, according to the National Institutes of Health.
Testosterone helps make sperm and maintains muscles and bones. Low testosterone can affect a man's sex drive and mood.
"Low testosterone by itself is not a disease," Anawalt says. "It is the combination of having symptoms and side effects associated with too little testosterone, plus a low blood testosterone level that you have confirmed on two or more occasions on early-morning blood tests."
Blood levels of testosterone change throughout the day.
Who needs testosterone therapy?
The FDA has approved testosterone in a patch, gel, and other forms. The approval is for men with low blood levels and an associated medical condition, such as a problem with the hypothalamus and pituitary gland, which control the making of testosterone.
According to guidelines from the Endocrine Society, testosterone can be considered for men with confirmed low blood levels (usually below 300 nanograms per deciliter) and consistent symptoms, including low libido.
Until more research is in, what's the best advice for men?
Getting a blood-level test of testosterone is crucial, experts agree. But they suspect many doctors don't check that before prescribing the testosterone.
"I don't think men should be fearful of it," Anawalt says of testosterone replacement therapy. "If they go to their doctor and it is truly low, the benefit exceeds any potential risk."
A man's health history should also factor into the decision about the therapy, Greenland says. "If I had had a heart attack, no, I wouldn't touch this.”
If a man has low testosterone, with no family history of heart attacks and no risk factors, "I would say proceed with caution," Greenland says. "Certainly you would want to be monitored by a doctor.”