Health

In a study of more than 3,600 Australian men age 70 and older, researchers found that those with lower-than-average testosterone levels were more likely to be frail or to develop frailty over the next several years.

The findings, published in the Journal of Clinical Endocrinology and Metabolism, add to evidence connecting testosterone loss to health problems in older men. But the question of what, if anything, to do about it remains open.

"It's too early to recommend testosterone therapy at this stage," lead researcher Zoe Hyde, of the University of Western Australia in Perth, told Reuters Health in an email.

"Large-scale, clinical trials are needed first to see if testosterone can prevent or treat frailty," she said, "and to assess the benefits and risks of therapy."

Testosterone helps men maintain their bone density, muscle mass and strength, and red blood cell production. Levels of the hormone naturally decline with age, and studies have linked lower testosterone levels in older men to problems such as diabetes, depression and bone fractures, and even to a shorter lifespan.

But whether waning testosterone levels are a cause of older men's health problems is not certain. And so far, studies have come to mixed conclusions as to whether giving older men extra testosterone can improve their physical function.

Some have found that testosterone -- given orally or by skin patch or injection, for instance -- seems to build older men's muscle mass and reduce body fat, but that those changes do not translate into greater mobility, strength or overall functioning.

For the current study, Hyde and her colleagues assessed frailty and testosterone levels in 3,616 men who were between the ages of 70 and 88; they were able to reassess 1,586 of those men four to seven years later.

At the first exam, 15 percent of the men were considered frail. That meant that they had at least three of five signs of deteriorating health: chronic fatigue; difficulty climbing a flight of stairs; difficulty walking more than one block; more than five major medical conditions, like diabetes, heart disease or arthritis; or an unintentional weight loss of more than 5 percent over several years.

In general, the researchers found, men whose total testosterone levels were below the average for the study group were more likely to be frail. Moreover, lower-than average levels of "free" testosterone were related to a greater risk of becoming frail over the next four to seven years.

Free testosterone is not bound to a protein in the blood, and is therefore more biologically active than other forms of the hormone.

The findings do not prove that declining testosterone was the reason for some men's frailty.

"We can never be certain of causality," Hyde explained, because men with certain conditions may develop lower testosterone levels before their diseases make themselves known.

However, she added that because the study followed men over time and linked lower testosterone to a greater risk of developing frailty in the future, the findings do suggest that the hormone may be directly involved in the frailty process.

"It is also biologically plausible," Hyde said, "as testosterone is important for maintaining bone density and muscle."

Still, no one knows whether testosterone replacement can prevent or treat frailty. There are also safety concerns about giving older men supplemental testosterone. Testosterone could, for instance, trigger an enlargement of the prostate gland or fuel the growth and spread of any existing prostate tumors. In addition, researchers are unsure what effect the hormone could have on older men's heart disease risk.

To help reduce their risk of frailty, Hyde said, the "best thing" older men can do right now is to lead a healthy lifestyle -- keeping their weight in the normal range, eating a well-balanced diet, staying physically active and not smoking.

SOURCE: here 4v1 Journal of Clinical Endocrinology and Metabolism, online April 21, 2010.