News Release

Mayo Clinic study finds definitive evidence relating to the role of estrogen in elderly males

Peer-Reviewed Publication

Mayo Clinic

A Mayo Clinic study, published in the December edition of the Journal of Clinical Investigation, provides new evidence that estrogen is dominant in the regulation of bone resorption in elderly men. Based on the study conclusions, men also need to be concerned about the long-term effects of bone loss, or osteoporosis.

The investigators studied 59 elderly men, with a mean age of 68 years. They were studied first under conditions of estrogen and testosterone replacement. After a baseline was established, they were divided into four subject groups and restudied: the absence of both hormones, the supplement of both hormones, the addition of estrogen alone and the addition of testosterone by itself.

The findings were surprisingly clear. Using this study design, the investigators found that estrogen played the key role in preventing the increase in bone resorption that occurred when both testosterone and estrogen were withdrawn. The findings also indicated that both estrogen and testosterone were important for the maintenance of bone formation in men.

Resorption, the natural act of bone breakdown, occurs throughout our lives as bones continually break down and re-form. As we age, this process becomes imperfect because bones break down more and regenerate less.

For many years there has been awareness of the role that estrogen plays in regulating the bone metabolism of women. When women reach menopause, they experience a dramatic and sudden loss of estrogen. In comparison, men have a constant and more gradual loss of both testosterone and estrogen over the course of their life. But due to the fact that testosterone is the dominant sex steroid secreted in men, it has always been thought that testosterone regulated bone metabolism in men. This new evidence contradicts these beliefs.

"We wanted to answer the question: In elderly men with a mature skeleton, which was more important to bone resorption - estrogen or testosterone?" says Dr. Sundeep Khosla, M.D., a Mayo Clinic endocrinologist and principal investigator of the study. "There have been cases of young males who could not produce or respond to estrogen and suffered from decreased bone mass. This suggested that there may be a link between estrogen and bone turnover in men.

"Men should begin thinking about osteoporosis prevention for themselves," says Dr. Khosla. "Straight estrogen therapy for men has to be very strictly controlled because of its feminizing effects," he explains. "But there are other treatments out there, which have an ‘estrogen-like’ effect on the skeleton without the feminizing side effects such as breast enlargement."

The study was funded by the National Institute on Aging. The National Institute on Aging, one of 25 institutes that constitute the National Institutes of Health, leads the federal effort to support and conduct basic, clinical, epidemiological and social research on aging and the special needs of older people.

According to Sherry Sherman, Director, Clinical Endocrinology and Osteoporosis Research National Institute on Aging, at the National Institutes of Health, "Although we’ve known for a long time that estrogen is critical to skeletal health in women, this study now confirms that estrogen also is essential in promoting optimal bone metabolism in aging men."

Co-investigators on the study were Drs. A. Falahati-Nini, B. L. Riggs, E. J. Atkinson, W. M. O’Fallon all of Mayo Clinic and R. Eastell of Northern General Hospital, Sheffield, United Kingdom.

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