Research presented to the Endocrine Society on June 5th is the second report linking deficiency of the sex hormone testosterone with increased death from all causes. In what was a relatively large study, this research seems to indicate that those who lack healthy levels of testosterone should be getting supplementation. It does NOT suggest that men with healthy levels of the hormone would benefit from even more testosterone, however.
“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,” said the lead author.
In the study, these scientists looked at death, no matter the cause, in nearly 800 men, ages 50 to 91 years, who were living in Rancho Bernardo, California. The participants have been members of the Rancho Bernardo Heart and Chronic Disease Study since the 1970s. At the beginning of the 1980s, almost one-third of these men had suboptimal blood testosterone levels for men their age.
The group with low testosterone levels had a 33 percent greater risk of death during the next 18 years than the men with higher testosterone. This difference was not explained by smoking, drinking, physical activity level or pre-existing diseases (such as diabetes or heart disease).
In this study, "low testosterone" levels were set at the lower limit of the normal range for young adult men. Testosterone declines slowly with aging in men and levels vary widely, with many older men still having testosterone levels in the range of young men. Twenty-nine percent of Rancho Bernardo men had low testosterone.
Men with low testosterone were more likely to have elevated markers of inflammation, called inflammatory cytokines, which contribute to many diseases. Another characteristic that distinguished the men with low testosterone was a larger waist girth along with a cluster of cardiovascular and diabetes risk factors related to this type of fat accumulation.
Men with low testosterone are three times more likely to have the metabolic syndrome than men with higher testosterone levels; metabolic syndrome is the name for the presence of three or more of these risk factors:
•waist measurement more than 40 inches in men (more than 35 inches in women),
•low HDL (good) cholesterol,
•high triglycerides (levels of fat in the blood),
•high blood pressure
•high blood glucose (blood sugar)
While the study lends support to the belief that supplemental hormone therapy may help older men with low testosterone levels, those who practice weight control and increase their physical activity may also live longer.
“It’s very possible that lifestyle determines what level of testosterone a patient has,” commented principal investigator, Elizabeth Barrett-Connor, M.D., UCSD Distinguished Professor of Family and Preventive Medicine and chief of the Division of Epidemiology. “It may be possible to alter the testosterone level by lowering obesity.”