National Institutes of Health (NIH)
February 28, 2017
As men age, the level of the male hormone testosterone usually drops. Some older men have levels far below what is normal for a young adult male. Doctors sometimes prescribe hormone treatment for such men to combat challenges they may have with sexual function, bone fractures, and other symptoms. But large, long-term studies of the benefits and risks of hormone treatment haven’t been conducted.
NIH’s National Institute on Aging (NIA) initiated the Testosterone Trials (TTrials) to find out whether the aging-related symptoms of low testosterone could be treated without significant side effects. In 7 trials at 12 medical centers across the United States, the researchers evaluated hormone treatment for men aged 65 or older who had a low level of testosterone. The trials are supported by NIA and other NIH components.
Participants received either testosterone gel or placebo gel. They were asked to apply it every day for 12 months. The men weren’t told which gel they were given. Regular blood tests assessed hormone levels. For those receiving testosterone gel, the dose was adjusted throughout the study period, if needed, to maintain the hormone level of a young man.
Findings from 3 studies on sexual function, walking, and vitality were reported last year. Results from the other 4 trials—on bone density, anemia, cognition, and cardiovascular risk—appeared in JAMA and JAMA Internal Medicine on February 21, 2017.
The researchers found an increase in bone density and strength among the men who received hormone treatment. However, a larger study over many years will be needed to determine whether increasing testosterone level can reduce a man’s risk of bone fracture.
Another trial assessed whether hormone treatment affects anemia, a condition in which the blood can’t supply enough oxygen to the body, causing fatigue and other symptoms. Anemia is often caused by low numbers of red blood cells. A greater percentage of men taking testosterone were no longer anemic (58%) after 12 months than those taking placebo (22%).
The researchers did not find a significant effect on memory or cognition from hormone treatment. They did find that treatment increased the build-up of plaque in the artery that supplies blood to the heart. Such build-up is associated with cardiovascular disease. However, the clinical implications are unclear. In another NIH-supported study published in the same issue of JAMA Internal Medicine, men who’d received hormone treatment after a diagnosis of low testosterone were less likely than other men to have had a heart attack, stroke, or other cardiovascular event. This study, however, was also not definitive.
“Clarifying the effects of testosterone on many major clinical outcomes such as cardiovascular events, fractures, and disability will require longer, larger scale trials,” explains Dr. Evan Hadley, director of NIA’s Division of Geriatrics and Clinical Gerontology.
Because the TTrials were conducted in older men with no apparent cause for low testosterone other than aging, these results don’t apply to men with low hormone levels for reasons other than aging. Any man considering hormone treatment should discuss the possible harms and benefits with a health care provider.