When used by males (aged 65 and above) with low levels of sex hormone, testosterone replacement therapy has led to health benefits and adverse effects alike, a lineup of five new studies has revealed.

Testosterone levels in men naturally start to decline as they age. The loss of this sex hormone could spell negative health effects, making some male patients undergo this therapy to replenish its levels artificially.

Mixed Outcomes

The group of five papers, published in JAMA and JAMA Internal Medicine, probed the role of testosterone treatment in different areas of health. Four of them delved on the effects on anemia, bone density, cognitive function, as well as coronary plaque buildup. The last study, an observational one, examined the association between testosterone therapy and overall cardiovascular well-being.

Researchers from University of Pennsylvania’s Perelman School of Medicine, with support from the National Institutes of Health (NIH) and testosterone product maker AbbVie, conducted seven clinical trials. Their Testosterone Trials (TTrials) covered 788 males ages 65 and above who had low testosterone levels.

Susan S. Ellenberg, the study’s lead biostatistician, clarified that TTrials are a single trial and randomization.

"People could be in only one trial, or they could be in multiple trials, but it was all sub-studies under one big umbrella trial,” she said.

Here are some key findings:

Cognition Trial — No improvements found in memory and other measures of cognition for men using testosterone gel.

Bone Trial  — Improvement in bone density and strength.

Cardiovascular Trial  — More plaque buildup in the coronary arteries of men receiving testosterone, but the number of heart attacks and other cardiovascular events was similar for males in testosterone and placebo groups.

Anemia Trial — Treatment helped correct anemia without identifiable cause as well as anemia stemming from iron deficiency.

Last year, the researchers published the first results from TTrials, including improved sexual function and mood.

Prospects For Testosterone Treatment

Senior author Dr. Peter Snyder said that TTrials were designed to investigate testosterone therapy’s effectiveness rather than risk, apart from the fact that they did not address long-term consequences. For Ellenberg, on the other hand, there’s no “overwhelming single answer” to the question of testosterone therapy’s positive health impacts.

“Treating 788 men for one year is far too few to draw conclusions,” Snyder added, pertaining to the significance of the increased coronary artery plaques and cardiovascular risk and stressing the need for a larger, longer-term trial in the future.

For some experts, the results of the $50 million trial were a letdown.

"The hopes for testosterone-led rejuvenation for older men are dimmed and disappointed if not yet finally dashed," said University of Sydney professor David J. Handelsman in an accompanying editorial.

Testosterone prescription for age-related deficiency started in 2000, with the advent of rub-on products led by AbbVie-manufactured Androgel.

In the United States (same as in Canada), up to 73 percent of testosterone prescribers are primary care providers, with only 18 percent of patients undergoing two blood tests prior to treatment. There was also a four-fold hike in the use of the therapy in the country from 2000 to 2011.

The FDA cracked down on over-prescription two years ago, warning of increased heart attack and stroke risks. Concerns around testosterone therapy also led the NIH to fund the TTrials.

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