Drop in testosterone levels is more likely to result from a man’s…

A new study finds that a drop in testosterone levels over time is more likely to result from a man’s behavioral and health changes than by aging. The study results will be presented Monday at The Endocrine Society’s 94th Annual Meeting in Houston.

“Declining testosterone levels are not an inevitable part of the aging process, as many people think,” said study co-author Gary Wittert, MD, professor of medicine at the University of Adelaide in Adelaide, Australia. “Testosterone changes are largely explained by smoking behavior and changes in health status, particularly obesity and depression.”

Many older men have low levels of the sex hormone testosterone, but the cause is not known. Few population-based studies have tracked changes in testosterone levels among the same men over time, as their study did, Wittert said.

In this study, supported by the National Health and Medical Research Council of Australia, the authors analyzed testosterone measurements in more than 1,500 men who had measurements taken at two clinic visits five years apart. All blood testosterone samples underwent testing at the same time for each time point, according to Wittert.

After the researchers excluded from the analysis any men who had abnormal lab values or who were taking medications or had medical conditions known to affect hormones, they included 1,382 men in the data analysis. Men ranged in age from 35 to 80 years, with an average age of 54.

On average, testosterone levels did not decline significantly over five years; rather, they decreased less than 1 percent each year, the authors reported. However, when the investigators analyzed the data by subgroups, they found that certain factors were linked to lower testosterone levels at five years than at the beginning of the study.

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