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Press Release
Study Links Low Testosterone to Mortality in Male Veterans
July 19, 2006
In a study of 858 men who received medical care at the Veterans Affairs (VA) Puget Sound Health Care System, those with low testosterone levels were found to experience higher rates of death than those with normal testosterone levels. The findings appear in the Aug.14 Archives of Internal Medicine.
The study, led by geriatric psychiatrist Molly M. Shores, MD, of VA and the University of Washington, found that men with low serum testosterone levels had an 88-percent greater risk for death than men with normal testosterone—even though both groups of men had a similar level of overall medical illness. The greater risk for death in men with low testosterone persisted even after researchers adjusted for other health differences between the groups of men.
Because testosterone levels may drop markedly with critical illness, Shores and her colleagues excluded men who died within the first year of the study to try to minimize the effect of this association. They believed that these men were most likely to have had low testosterone levels due to a critical illness.
"Even after we excluded men with early deaths, however, men with low testosterone continued to have a 68-percent greater risk for death than men with normal testosterone levels," said the researcher.
Shores stressed that the men with low testosterone, on average, had levels lower than those of most older men. The increased risk for death occurred in these men, and not in those with normal testosterone levels.
The researcher said it is unclear why men with low testosterone had higher death rates. Since low testosterone is associated with chronic medical illnesses, low testosterone may just be a marker for overall poor health, she noted. The level of chronic medical illness, however, was similar between the veterans with low testosterone who died and those with normal levels of testosterone who survived.
Shores' investigation followed men, age 40 and over, who had been seen at the VA between October 1994 and December 1999, and who had their blood testosterone levels checked more than once during that period. Most men were outpatients. Individuals with prostate cancer were excluded from the study. Mortality data was obtained through December 2002.
Shores pointed out that she conducted this study after being surprised to find this same association in an earlier study. "I had been looking at low testosterone levels in veterans with newly diagnosed depression. Finding an association between low testosterone and mortality was not part of my hypothesis."
One key limitation of the new study, she noted, was the difficulty of accurately measuring testosterone levels in the lab. Further, the study sample—veterans receiving care at VA—reflects a sicker group of men than would be found in a random sampling of men in the Seattle area. "Most of our patients had at least five chronic medical conditions," Shores explained.
Also, the study was retrospective—that is, based on patients' medical histories—and thus could not identify and adjust for all factors that may have influenced the results.
Shores said the study in no way addresses or advocates prescription treatment for low testosterone levels, but it does show the need for further research to clarify the association between low testosterone and mortality.
Funding for this research came from the Royalty Research Fund of the University of Washington and a VA grant. Other investigators included Alvin M. Matsumoto, MD; Kevin L. Sloan, MD; and Daniel R. Kivlahan, Ph.D., all of VA and the University of Washington.
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