For men who use testosterone-replacement therapy because of low levels of the hormone, the treatment does not appear to be associated with any “major” heart risks, according to a new study.
The study, published Friday in the New England Journal of Medicine, found that in men with low testosterone who have cardiovascular disease or are at high risk of it, taking testosterone-replacement therapy was not associated with an increased incidence of serious cardiac events like heart attack or stroke.
There were “no apparent clinically meaningful differences” in the incidence of cardiovascular events observed between two groups in the study, the researchers wrote.
But the researchers, from the Cleveland Clinic and other US institutions, found a higher incidence of irregular heartbeat, acute kidney injury and pulmonary embolism in the testosterone group, although they occurred at low rates. The findings of the study – which the researchers called “the largest trial” yet of tesosterone replacement therapy in men – were presented Friday at an annual meeting of the Endocrine Society in Chicago.
“Although the trial showed some evidence that testosterone treatment may be safe for men with low levels of testosterone, these findings should not be used as a justification for widespread prescription of these products to large numbers of men,” the study’s senior author, Dr. Steven Nissen, chief academic officer of the Heart, Vascular & Thoracic Institute at the Cleveland Clinic, said in a news release Friday. He added that men with low testosterone should not try to treat it on their own, without the help of a medical professional.
“The market is booming with so-called ‘natural’ testosterone boosters, and men need to be careful,” Nissen said. “These products have not been evaluated in rigorous clinical trials and they have not been approved by the FDA to treat low testosterone levels.”
The new study included data on more than 5,000 men, ages 45 to 80, who had preexisting or a high risk of cardiovascular disease, who reported symptoms of low testosterone and who were measured to have low testosterone levels. The men were randomly assigned to receive a daily testosterone gel or a placebo for an average of 22 months. The first participant was enrolled in May 2018.
The researchers found that there was a major adverse cardiac event in 7% of men in the testosterone group, compared with 7.3% of those in the placebo group.
In 2015, the US Food and Drug Administration issued guidance that required manufacturers of approved testosterone products to conduct clinical trials to determine whether testosterone-replacement therapy is associated with a higher risk of cardiovascular events, and the agency cautioned that prescription testosterone products are approved only for men who have low testosterone levels caused by certain medical conditions.
The new study was supported by AbbVie, Acerus Pharmacueticals, Endo Pharmaceuticals and Upsher-Smith Laboratories.
“Because testosterone deficiency is not a life-threatening condition, uncertainty about cardiovascular outcomes has weighed on treatment decisions by clinicians and patients,” Dr. Michael Lincoff, lead author of the study and vice chair for research in the Cleveland Clinic Department of Cardiovascular Medicine, said in the news release. “Our findings may facilitate a more informed consideration of the potential benefits and risks of testosterone therapy among middle-aged and older men with hypogonadism.”
A roundup of five testosterone studies published in 2017 in JAMA and JAMA Internal Medicine found that testosterone treatment improved bone density and anemia in men older than 65 who had low testosterone levels and was associated with a lower risk of cardiovascular events, but such therapy appeared to be associated with plaque buildup in coronary arteries.
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Dr. Caroline Messer, an endocrinologist at Lenox Hill Hospital in New York City, said in 2017 that she is visited “all the time” by people of all ages who are shopping for a prescription.
Although she hasn’t personally seen any extreme medical harms in those who take testosterone, she has heard complaints, including testicular shrinkage. But she’s mainly seen positive effects in the men taking testosterone.
“I mostly see improved energy and improved sexual drive and maybe a little bit of weight loss, a little more muscle, a little less fat,” Messer said. Still, worries about the unknown health risks and says longer-term studies are needed.
CNN’s Susan Scutti contributed to this report.