For aging men, testosterone may not be the magic bullet after all.
Only a fraction of men actually experience a severe drop in the male hormone as they age, according to research published Wednesday in the New England Journal of Medicine.
So, as hormone therapy gains traction as a treatment for a wide range of "male menopause" symptoms - including sexual dysfunction, physical decline and mental health issues - many men may be taking testosterone unnecessarily, says Ilpo Huhtaniemi, a professor of reproductive endocrinology at Imperial College London and an author of the study.
"It's an expensive placebo," he says.
Until now, it was assumed that because aging men reported similar symptoms as young men suffering from low testosterone levels, the testosterone itself was the culprit.
"But the connection was never clearly shown," says Dr. Huhtaniemi.
Instead, many of those symptoms may be due to garden-variety aging, obesity and other health issues.
While all women go through menopause, not all men experience the male equivalent, Dr. Huhtaniemi says.
He and his co-authors measured the testosterone levels of more than 3,000 men aged 40 to 79 from eight European countries and asked for details about their sexual, physical and psychological health.
Of the 32 symptoms commonly associated with male menopause (known clinically as "late-onset hypogonadism"), only three were strongly associated with low testosterone levels in middle-aged and elderly men. They were all sexual symptoms: decreased frequency of morning erection;
decreased frequency of sexual thoughts, and
erectile dysfunction.
The researchers found that only 2 per cent of men in the study experienced low levels of testosterone and these three symptoms together.
Dr. Huhtaniemi and his co-authors suggest that this is a reasonable threshold for diagnosing late-onset hypogonadism, and that the condition is likely being over-diagnosed.
Six other physical and psychological symptoms - an inability to engage in vigorous activity; an inability to walk one kilometre; an inability to bend, kneel or stoop; a loss of energy; sadness, and fatigue - were weakly associated with low testosterone in the study.
The balance of the symptoms commonly connected with male menopause, such as poor sleeping patterns, poor concentration, feeling worthless, nervousness and anxiety were found to be unrelated to testosterone levels.
Dr. Huhtaniemi acknowledges that further study is required to determine the benefits and risks of testosterone therapy for the relatively small number of cases that may warrant it. Potential risks include prostate cancer and stroke.
His study may be bad news for those he calls "testosterone enthusiasts," physicians and drug companies who promote the hormone as a cure-all. Testosterone therapy has increased in the United States by 400 per cent since 1999, he points out.
But Dr. Huhtaniemi sees his findings, which are part of the European Male Aging Study funded by the European Union, as "good news."
"We shouldn't medicalize normal aging."
Toronto physician Shafiq Qaadri, author of The Testosterone Factor: A Practical Guide to Improving Vitality and Virility, Naturally, agrees. But he says there still may be options for men who fall outside Dr. Huhtaniemi's strict criteria.
"There's a lot of quiet suffering out there that we as physicians are invited to deal with," he says.
And while he's not in favour of blanket testosterone prescriptions, he does see room in the future for individualized monitoring of testosterone levels, starting perhaps with a baseline test at age 30.
Dr. Qaadri also encourages patients to make lifestyle changes that may protect their testosterone levels naturally and prevent some effects of testosterone decline, such as bone loss. A major factor, for instance, can be weight gain around the torso, which zaps testosterone and boosts estrogen.
"It's like having ovaries in your gut."