Life Extension Update
Low testosterone levels in older men increase the risk of death during 4 year average follow-up
A report published in the August 14/28, 2006 issue of American Medical Association journal Archives of Internal Medicine, revealed a correlation between reduced levels of the male hormone testosterone and an increased risk of mortality during up to 8 years of follow-up. Testosterone levels in men decrease by approximately 1.5 percent per year after age 30, which can eventually result in muscle mass and bone density reduction, diminished energy and libido, and depression and irritability.
Molly M. Shores, MD, and colleagues at the Veterans Administration Puget Sound Health Care System and University of Washington, Seattle, analyzed the association between testosterone levels and death in 858 male veterans over the age of 40. The participants’ testosterone levels were measured at least twice between 1994 and 1999. Subjects were followed through 2002, and any deaths among the group were noted.
Nineteen percent of the participants were found to have a low total testosterone level of less than 250 nanograms per deciliter, or a free testosterone level of less than 0.75 nanograms per deciliter. Fifty-three percent had normal testosterone levels and 28 percent had tests that measured an equal number of low and normal levels. While only 20 percent of the men with normal testosterone died during follow-up, deaths occurred among 24.6 of those with equivocal levels and 35 percent of those with low levels. After adjustment for age, illness and other factors, men whose testosterone levels were classified as low experienced an 88 percent adjusted increased risk of dying over the course of the follow-up compared to those with normal levels. To reduce the effect of acute illness on the finding, the researchers reanalyzed the data excluding men who died within the first year of follow-up, yet they still found an increase of 68 percent in the risk of dying among men with low testosterone.
"The persistence of elevated mortality risk after excluding early deaths suggests that the association between low testosterone and mortality is not simply due to acute illness," the authors conclude. "Large prospective studies are needed to clarify the association between low testosterone levels and mortality."
The exact causes of the age-related reduction in testosterone levels is not known; it is probably the result of a combination of factors, including increased body fat (and therefore increased aromatase activity), oxidative damage to tissues responsible for the production of testosterone, and declining levels of precursor molecules such as DHEA. The results of the decline, however, are strikingly apparent.
When testosterone levels are measured, it is critical to determine the levels of both free and total testosterone to understand the cause of any observed symptoms of deficiency or excess (Pardridge WM 1986).
The Life Extension Foundation believes that a comprehensive battery of tests along with a careful physical examination, is helpful in detecting hormonal imbalances in aging men. If testing is conducted, it is important to remember that blood levels of both free and total testosterone vary widely among individuals, making it difficult to establish a general threshold for treatment. However, levels are quite consistent within individuals, so it is helpful for men to have multiple tests over time to determine trends and individual thresholds for treatment.
One reason testosterone production may decline is because of oxidative damage directed at the tissues that synthesize testosterone. A Chinese study examined the role of antioxidants in male hormone imbalance or partial androgen deficiency of aging men. The article’s authors note that antioxidants (including vitamin A, vitamin E, zinc, and selenium) all support testosterone production (He F et al 2005).
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