TUESDAY, Nov. 5 (HealthDay News) -- New research suggests that men who take testosterone supplements after undergoing a minor cardiac procedure are more likely to suffer strokes, heart attacks or die.

But it's not clear if there's truly an extra risk for these men. And urologists aren't calling for caution beyond the usual warnings about potential overuse of testosterone supplements.

"The investigators simply do not know all of the potential differences between the men who were treated with testosterone and those who were not," said Dr. Bradley Anawalt, an endocrinologist and chief of medicine service at the University of Washington Medical Center in Seattle. He was not involved with the study.

VA Eastern Colorado Health Care System cardiologist Dr. P. Michael Ho, a study co-author, acknowledged that the results don't confirm that testosterone supplements are especially risky for men with suspected heart problems. However, "this hopefully provides information that doctors can use when they discuss with their patients about whether to start or continue testosterone therapy," he noted.

Testosterone therapy has become a hot topic in doctor's offices in recent years as late-night TV ads warn male viewers that "low T" could explain fatigue and low libidos. A study earlier this year found that the use of testosterone therapy by U.S. men aged 40 and up tripled between 2001 and 2011.

Some urologists and endocrinologists warn that doctors are overprescribing the supplements, which can cost thousands of dollars a year and are linked to side effects such as blood clots, male breast growth and infertility.

In the new study, researchers looked at the medical records of more than 8,700 men in the United States who underwent angiographs, a procedure that uses scans to examine blood flow in the body. Angiographs are different from angiograms, in which doctors send catheters up into an artery to determine whether blood vessels are clogged.

All of the men in the study had testosterone levels that were considered to be on the low side; on average, the men were in their early 60s. A total of 1,223 of the men used testosterone therapy after their angiographs.

The researchers tracked the men for an average of 28 months and adjusted the study's statistics so they wouldn't be thrown off by high or low numbers of men with heart disease (almost all had signs of it). The investigators found that the men in the study were about 30 percent more likely to suffer a heart attack or stroke and to die after going on testosterone therapy, although these conditions weren't extremely common overall. (Nine percent of the men died.)

The study has limitations. It's not clear why men who went on testosterone therapy sought it in the first place. And the study didn't examine the benefits that the treatment could have brought to the men in terms of things like their sex lives, energy levels and overall happiness.

Study co-author Ho pointed out that the researchers tried to account for the possible effect of health conditions such as diabetes. It's conceivable that testosterone supplements could worsen sleep apnea and boost the risk of blood clots, he suggested.

Dr. John Amory, a professor of medicine at the University of Washington Medical Center, said the findings shouldn't worry people because they could easily be misleading. But they do point to the importance of research that will do a better job of identifying any risks from testosterone supplements. "The final verdict will wait," he said.

Amory added that testosterone treatment is definitely a good idea in certain cases, such as in a young man who's lost his testicles to cancer. In other men, especially those who are older and sicker, it's not as clear that the benefits outweigh the risks, he said.

The study appears in the Nov. 6 issue of the Journal of the American Medical Association.

More information

For more about testosterone, try the U.S. National Library of Medicine.