TUESDAY, Aug. 15 (HealthDay News) -- Low testosterone may boost death risk in men over 40, a new study finds.

A U.S. team found that older males with relatively low testosterone had an 88 percent increased risk of death compared with their counterparts with normal testosterone levels, researchers report.

"This is really an unusual finding. The exact mechanism of this needs to be worked out," said lead researcher Dr. Molly M. Shores of the Veterans Administration Puget Sound Health Care System and University of Washington, Seattle.

The report was published in the Aug. 14/28 issue of the Archives of Internal Medicine.

As men age, their testosterone levels gradually decline. After 30 years of age, levels decrease by about 1.5 percent per year. Low testosterone levels can result in decreased muscle mass and bone density, insulin resistance and low sex drive, as well as less energy, more irritability and feelings of depression, the researchers noted.

In the study, Shores and her colleagues looked at the whether low testosterone levels were associated with an increased risk of death in 858 men over 40.

Among older men, 19 percent had low testosterone levels, 28 percent had an equivocal testosterone level, meaning that their tests revealed an equal number of low and normal levels, and 53 percent had normal levels.

"Low testosterone in older men was associated with an increased risk for mortality," Shores concluded. During 4.3 years of follow-up, 20.1 percent of men with normal testosterone levels died, compared with 24.6 percent of the men with equivocal levels and 34.9 percent of the men with low testosterone levels, Shores's team found.

Testosterone levels can be affected by illness, surgery and other medical problems. But even when the researchers excluded men who had died within the first year of follow-up, those with low testosterone levels were still 68 percent more likely to die compare to men with normal levels of the hormone, Shores noted.

It's not yet clear whether low testosterone helps cause illness and death, Shores said. Men who have chronic illnesses typically have low testosterone levels, she noted. So, "it may be that men who are ill have a low testosterone level and then they have a higher death rate," she said.

Shores suggests that men who think they might have low circulating testosterone discuss it with their doctor. Testosterone supplementation is an option, but Shores cautioned against it, saying the risk and benefits of such treatment aren't yet known.

One expert said the findings aren't overly surprising.

"This confirms similar data from the Massachusetts Male Aging Study," said Dr. Andre T. Guay, the director of the Center for Sexual Function/Endocrinology at the Lahey Clinic in Peabody, Mass. "Shores's diagnosis of low testosterone is lower than others use, so people with really low testosterone levels are at risk," he added.

More information

There's more on low testosterone at the U.S. National Library of Medicine.

SOURCES: Molly M. Shores, M.D., VA Puget Sound Health Care System and University of Washington, Seattle; Andre T. Guay, M.D., director, Center for Sexual Function/Endocrinology, Lahey Clinic, Peabody, Mass.; Aug. 14/28, 2006, Archives of Internal Medicine

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