Watch any football game or a news program, and you’re almost sure to see one of those commercials about how a-little-dab’ll-do-ya of testosterone can banish the “low-T” blues and put spark back into your life.
The ads work. Almost 3 percent of American men aged 40 and older have been prescribed testosterone replacement therapy. According to figures compiled by BloombergBusinessweek, sales of testosterone drugs could reach $5 billion by 2017.
But a study released Tuesday in the Journal of the American Medical Association is sure to raise questions about the wisdom behind the testosterone rush. It finds that among men with previous heart troubles and low testosterone levels, the use of 'low-T' therapy boosted the risk of serious problems including heart attack, stroke — and death.
Researchers at the University of Texas at Southwestern Medical Center in Dallas reviewed records from more than 8,700 men with low-T levels who underwent coronary angiography — a procedure that uses dye and X-rays to peer into heart arteries — in the Veterans Affairs system between 2005 and 2011.
Of nearly 7,500 guys who did not get extra T, about 1 in 5 had bad cardiovascular outcomes, including stroke, heart attack or death. In the more than 1,200 men who got testosterone, nearly 1 in 4 had those terrible problems, an increased risk of nearly 30 percent.
The researchers concluded that taking testosterone came with an increased risk of an adverse outcome.
That’s not the whole story, though. Dr. Anne Cappola of the Perelman School of Medicine at the University of Pennsylvania wrote in an accompanying editorial: “The most important question is the generalizability of the results of this study to the broader population of men taking testosterone ….”
That’s a very big caveat: By definition, all the men in the study were older than 60 and all had heart problems. It's still not clear whether those same risks apply to younger, healthier guys.
“These were sick, older veterans,” Dr. Michael Ho, a cardiologist with the VA Eastern Colorado Health Care System who helped direct the study, said in an interview. Many were obese, had diabetes, and other ailments, he said.
Dr. Bradley Anawalt, an endocrinologist and professor of medicine at the University of Washington, agreed — but only to a point.
“This is a modestly cautionary study about giving testosterone to men over 60 with multiple” health problems, he said in an interview.
Some men might do just fine with a little extra T, experts say.
Just ask writer Andrew Sullivan, who helped popularize testosterone therapy. Fifteen years ago he was lethargic, depressed, and suffering from drug-induced nausea brought on by anti-HIV medications. He was 35 years old, but his testosterone levels “were below those of most 80-year-olds. I was tested at the time and my doc was shocked by the low levels,” he told NBCNews.com in an email.
Sullivan began taking testosterone injections and was transformed. He wrote a widely read and influential essay for The New York Times magazine called "The He Hormone" that extolled the drug’s benefits. Today, Sullivan, 50, still takes testosterone via four-month implants.
“I have energy, am leaner, have more muscle mass, am motivated to work out and can sustain the kind of focus that a blog like mine demands,” he said.
Those are all reasons why many men beg their doctors for the supplement. Ho said this new study should inform doctor-patient discussion by helping to put testosterone use in better perspective.
Sullivan is far from alone, said Anawalt.
“I have men coming into my clinic who want to take it,” he said. “Maybe they are a little low but not truly hypogonadal. I can say, ‘Here’s a study that raises concerns.’ So I think it’s helpful from that perspective. But if these guys are 30, 40, 50 and don’t have heart disease, well, the study doesn’t relate to them, so if they read it carefully, they can call my bluff.”
Like all so-called observational studies, this one has several limitations. For example, it’s not known how many of the men taking testosterone were properly diagnosed and tested for levels before being given a prescription. Morning blood sampling is the preferred way to test for testosterone, and most endocrinologists prefer two separate tests. Levels below 300 nanograms per deciliter of blood is considered low.
If you’re shrugging and wondering what to make of it all, you’re like many experts. Almost all agree there are many unknowns about testosterone supplementation. That’s why, Anawalt explained, medicine has swung back and forth over the past two decades.
At first, many physicians worried giving men any extra testosterone could lead to prostate cancer, something Sullivan said his doctor discussed with him 15 years ago. As anxiety over that issue moderated, doctors realized that a large group of men had low T levels, Anawalt said, and that “there were now lots of options to treat."
Sullivan started with injections, which cause testosterone spikes, a problem avoided by newer implants and gels.
“T may have positive effects for bone, sex life, muscle, moods. So it’s gone from something of a boutique area of medicine to mainstream," Anawalt said.
But there’s been no huge, comprehensive study akin to the famous Women’s Health Initiative that tracked hormone replacement outcomes in post-menopausal women. Nor is there likely to be given the enormous costs and complicated logistics.
That leaves doctors looking at a mixed bag of study results.
For example, the current study was partly inspired by a 2010 publication in the New England Journal of Medicine that examined older men with an average age of 74. These men also had a high burden of chronic disease. The men who were taking testosterone had more cardiovascular events such as heart attacks.
But last year, a larger study published in the Journal of Clinical Endocrinology and Metabolism showed that among male veterans over 40, those taking testosterone had lower rates of death than those who were not.
To further confuse matters, recent research pointed out that testosterone does not work alone. Men also need estrogen.
For men with drastically low testosterone, like Sullivan, the drug has been a boon. Other than slightly smaller testicles, he said, there have been “no downsides at all from my perspective.”
But experts like Anawalt worry that many men now see testosterone as an elixir. If nothing else, the current study should give them pause. “Rational people should be thinking about this. Like, ‘Wait a minute. Do I really want to take this?’”
Brian Alexander is a frequent contributor to NBC News and a co-author of “The Chemistry Between Us: Love, Sex, and the Science of Attraction.”