Low Testosterone Linked To Shorter Life In Older Men

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Main Category: Men's health
Also Included In: Endocrinology;  Obesity / Weight Loss / Fitness
Article Date: 06 Jun 2007 - 11:00 PDT

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A new US study suggests that having low testosterone may shorten the lives of men over 50.

Researchers at the Department of Family and Preventive Medicine at the University of California, San Diego (UCSD) School of Medicine conducted a long-term study involving 800 men over an 18-year period and found that those with low testosterone carried a 33 per cent higher risk of death compared with those who had higher levels.

The study was reported to the Endocrine Society annual meeting in Toronto earlier this month and is one of a selection of articles published in The Endocrine Society's ENDO 07 Research Summaries Book. It was funded by the National Institute on Aging in the US and the American Heart Association.

Assistant professor and one of the report's authors, Dr Gail Laughlin said that:

"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."

She referred to the study's duration, averaging 18 years, and said this "strongly suggests that the association between testosterone levels and death is not simply due to some acute illness".

The study participants were men aged from 50 to 91 years, who were living in Rancho Bernardo, California. They had been attending the Rancho Bernardo Heart and Chronic Disease Study since the 1970s.

Ten years later, by the start of the 1980s, nearly one third (29 per cent) of the men had low blood testosterone. For the purpose of this study, low testosterone was defined as the lower limit of the range normally found in young male adults.

The nearly one third of men with low testosterone showed a 33 higher risk of death over the 18 years compared with men with higher testosterone. And factors such as smoking status, alcohol consumption, physical activity and pre-existing diseases like diabetes and heart problems did not account for the difference.

Testosterone levels tend to fall as men get older and the range varies widely.

Laughlin and colleagues found that the men with low testosterone were more likely to have:

• Higher levels of inflammatory cytokines; these are biomarkers for inflammation which contribute to several diseases.
• Larger waist measurement.
• A cluster of cardiovascular and diabetes risk factors, collectively called the "metabolic syndrome" that is linked to having a larger waist.

The cluster of factors that characterize metabolic syndrome includes a waist bigger than 40 inches (35 inches for women), low levels of good cholesterol (HDL), high levels of blood fats (triglycerides), high blood pressure and high blood sugar.

Laughlin and colleagues also found that men in the low testosterone group were three times more likely to have metabolic syndrome than men in the higher testosterone group.

Although the study may suggest that hormone supplements might help older men with low testosterone, the authors suggest that weight control and exercise would be a better way to influence longevity.

Principal researcher and UCSD Distinguished Professor of Family and Preventive Medicine and chief of the Division of Epidemiology, Dr Elizabeth Barrett-Connor said:

"It's very possible that lifestyle determines what level of testosterone a patient has."

And she added that:

"It may be possible to alter the testosterone level by lowering obesity."

The authors took pains to point out that while this study suggests low testosterone may be linked with shorter life, it does not suggest that higher testosterone would be linked with longer life.

However, researchers at UCSD are planning to hold a randomized controlled trial to see if testosterone supplements can safely promote longer life.

Barrett-Connor said that while they were excited by the findings, they were not suggesting that men should start taking testosterone supplement in the belief it will prolong their lives. "We're not ready to take this to the prescribing pharmacist," she cautioned.

There are those who say that women tend to live longer because they have higher estrogen and lower testosterone, but the fact is, said Barret-Connor, "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," she said.

Click here for the Endocrine Society.

Written by: Catharine Paddock
Writer: Medical News Today
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today