Men who take testosterone treatments or use gel containing the hormone may have an increased risk for heart attack, stroke and early death, the Associated Press reported.
Based on a study conducted by the Veteran Affairs, men who used testosterone supplements were nearly 30 percent more likely to die, have a heart attack or a stroke after three years of use than men with low hormone levels that didn't take the supplement.
Researchers analyzed 8,700 veterans with low levels of testosterone, the main male sex hormone, in the nationwide study. The participants had undergone a heart imaging test -many had risk factors for heart problems, including blocked arteries. The study found that the risks linked with testosterone were similar in men with and without existing heart problems.
Dr. Michael Ho, cardiologist at the University of Colorado and lead author of the study, told ABC News he was surprised when he found that the risks of testosterone treatments appeared to be the same for men regardless of whether they had existing coronary disease.
"This study provides some information about potential adverse effects [of testosterone supplementation]," Ho said. "This study should help inform the discussion between patient and providers about the risks and benefits before making an individualized decision."
The new research raise concerns about the widely used testosterone gels, patches and injections that are primarily used to rectify low sex drives, fatigue and aging.
The study found that nearly 26 percent of men using hormone supplements suffered from a heart attack, stroke or died from any cause within three years of the heart test, compared with 20 percent of nonusers.
Ho said the new research does not prove testosterone caused heart attacks, strokes or death "but echoes a previous study in older men and should prompt doctors and patients to discuss potential risks and benefits of using the products," according to the AP.
Researchers said it's still unclear how the hormone might increase heart risks, but evidence show that testosterone might make blood substances called stick together, which could cause in blood clots, according to the researchers.
Dr. Anne Cappola, a hormone expert at University of Pennsylvania and an associate journal editor, said more research is needed on testosterone supplements.
"There is only anecdotal evidence that testosterone is safe for these men," she said in a statement. "In light of the high volume of prescriptions and aggressive marketing by testosterone manufacturers, prescribers and patients should be wary."
