The loss of this sex hormone could spell negative health effects, making some male patients undergo this therapy to replenish its levels artificially. Hypogonadism affects only 0.1 percent of men in their 40s and just 5.1 percent of men in their 70s.
Many men age 65 and up who have low levels of testosterone say their sense of well-being, not to mention their libido, isn't what it used to be.
This medicalization of male aging, which began about a decade ago, worked. Testosterone therapy was good for the bones, but didn't help memory.
The use of testosterone-replacement therapy has almost doubled in recent years, from 1.3 million patients in 2009 to 2.3 million in 2013, according to the U.S. Food and Drug Administration.
And the findings of five studies released Tuesday aren't likely to clear up the confusion.
But previous studies have repeatedly failed to find rigorous proof of these claims, despite the vigorous advertisements aimed at convincing middle-aged and older men that they need testosterone to combat "Low T".
Study Rundown: Decrease in serum testosterone commonly occurs in elderly men.
Half were given testosterone gel, applied to the skin, while the other half were given a placebo gel containing no testosterone. Among men using the testosterone gel, there were statistically significant improvements in lumbar spine and hip bone density and bone strength. Four of them delved on the effects on anemia, bone density, cognitive function, as well as coronary plaque buildup.
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Further, testosterone treatment also increased haemoglobin concentrations, corrected the anaemia of men who had no other identifiable cause of anaemia and corrected the blood levels of men who had an identifiable cause, such as iron deficiency. The fifth study is observational and examines the links between testosterone treatment and overall cardiovascular health. At the start of the study, 493 of the participants had age-associated memory impairments (defined by both the men's own reports and by the results of memory tests). Additional funding was provided by the maker of AndroGel, AbbVie, which also supplied the drug, which is customary in clinical trials. Testosterone treatment had no effect on memory or other cognitive function.
Those three studies could be viewed as neutral or even mildly promising for testosterone supplements.
But for cardiovascular health, there was an effect-a bad one. "However, the increase of plaque buildup in the coronary artery shows that this treatment may also have some risk". The study found that noncalcified plaque volume increased significantly more in the testosterone-treated group compared to controls, as measured by coronary computerized tomographic arteriography, a special type of heart scan. Arterial plaque is considered an early sign of heart disease. Additionally, the study sample was small and had limited ethnic diversity. A larger, longer study would be needed to confirm the findings.
The results are from the final four studies in a seven-part project mostly funded by the National Institute on Aging, involving almost 800 US men aged 65 and older with low testosterone levels. Dozens of studies have tackled the question, but the results "point in lots of different directions", he says. The Bone Trial included 189 of the 790 men in the overall study. "Rather, low testosterone levels due to obesity and other aging comorbidities are better addressed by lifestyle measures directed at those comorbidities".
"Testosterone and synthetic androgens have valuable medical applications but a key lesson is that such novel indications should be established by efficacy and safety studies and not preceded by wide-scale, off-label adoption", he wrote.
The hazard ratios similarly favored testosterone therapy for stroke and TIA and for the cardiac events separately, T. Craig Cheetham, PharmD, of the Southern California Permanente Medical Group in Pasadena, reported in JAMA Internal Medicine.
FMI: You'll find all the studies mentioned - and the editorial - in the February 21, 2017, issues of JAMA and JAMA Internal Medicine.