Older men with clogged arteries who took testosterone therapy seemed to have a lower risk of heart attacks than men who did not take the hormone, a study suggested.
Testosterone is currently considered risky to the heart, and the US Food and Drug Administration mandated last year that manufacturers of all approved testosterone products add labels to describe these dangers, which include heart attack and stroke.
The methods of the study were observational one of the weakest kinds of scientific research but its authors said the results should lead to more rigorous trials on the hormone therapy in the future.
The study by Intermountain Medical Center Heart Institute in Salt Lake City included 755 men, aged 58 to 78, with severe coronary artery disease and low testosterone.
Those who did not take testosterone as part of their follow up were 80% more likely to suffer a heart attack, stroke, or death from a cardiovascular event in the next three years.
After a year, 64 patients who were not taking testosterone supplements suffered major adverse cardiovascular events, compared to 21 taking testosterone.
After three years, 125 patients not on testosterone therapy patients suffered major adverse cardiovascular events, compared to 60 patients receiving the hormone.
The findings were presented at the American College of Cardiology conference in Chicago.
"Although this study indicates that hypo-androgenic men with coronary artery disease might actually be protected by testosterone replacement, this is an observational study that doesn't provide enough evidence to justify changing treatment recommendations," said cardiologist Brent Muhlestein, co-director of cardiovascular research at the Intermountain Medical Center Heart Institute.
"It does, however, substantiate the need for a randomised clinical trial that can confirm or refute the results of this study."