The results of a study presented on June 5, 2007 at The Endocrine Society for publication in their ENDO 07 Research Summaries Book determined that men over 50 whose levels of the hormone testosterone are low had a greater risk of dying within an eighteen year period than men with higher levels.

University of California, San Diego School of Medicine chief of the Division of Epidemiology Elizabeth Barrett-Connor, MD and colleagues evaluated data from nearly 800 men aged 50 to 91 who enrolled in the Rancho Bernardo Heart and Chronic Disease Study in the 1970s. Twenty-nine percent of the participants had testosterone levels at the lower limit of the normal range for their age at the beginning of the 1980s. These men experienced a 33 percent greater risk of dying from any cause over the ensuing 18 years than men with higher levels. Participants with decreased testosterone had a greater incidence of elevated inflammatory cytokines, as well as greater waist girth and other metabolic syndrome risk factors.

"Conventional wisdom is that women live longer because estrogen is good and testosterone is bad," Dr Barrett-Connor stated. "We don’t know. Maybe the decline in testosterone is healthy and comes with older age. Maybe the decline is bad and is associated with chronic diseases of aging."

"The new study is only the second report linking deficiency of this sex hormone with increased death from all causes, over time, and the first to do so in relatively healthy men who are living in the community," announced coauthor Gail Laughlin, PhD, who presented the findings. "We have followed these men for an average of 18 years and our study strongly suggests that the association between testosterone levels and death is not simply due to some acute illness."