Source: Am J Med Genet  |  Posted 7 years ago

By Bonnie Darves

SEATTLE, WA -- October 8, 2004 -- Sex hormone levels may play a greater role in determining which men will be at higher risk of osteoporosis-related fractures than previously thought, according to a study presented at the American Society for Bone and Mineral Research annual meeting.

While low levels of free testosterone are a predictor of hip bone loss, declines in estradiol levels play a stronger role than testosterone, the study's lead author, Jane Cauley, DrPH, associate professor of epidemiology, University of Pittsburgh School of Medicine, Pennsylvania, said on October 5th.

While men with higher levels of free testosterone and total testosterone have less bone loss than men with lower testosterone levels, that relationship does not translate into higher bone mineral density (BMD), she said.

Dr. Cauley and colleagues in the Osteoporotic Fracture in Men Study conducted a study in 2,619 men aged 65 and older.

"Men who experienced the greatest decline in estradiol experienced greater bone loss, independent of their testosterone levels," Dr. Cauley said. "We found that estradiol, not testosterone, is the major predictor of BMD and bone loss rates in men, regardless of weight, age, and baseline BMD."

She said that men who had the largest declines in estradiol over the 1.8 years of the study lost 0.72% total hip BMD annually, compared with a decline of 0.42% in those in the top baseline estradiol quintile. Lumbar spine BMD also was 7% higher in the estradiol top-quintile group than in the bottom-quintile group, Dr. Cauley noted.

She added that her team members were somewhat surprised to find no correlation between advancing age and estradiol levels in the cohort. There were men with relatively high baseline estradiol levels in all age groups, including the group older than 80 years, but 65% of men experienced some estradiol loss over the study period, she added.

[Presentation title: "Sex Steroid Hormones in Older Men: Cross-Sectional and Longitudinal Associations With Bone Mineral Density (BMD). The Osteoporotic Fracture in Men Study (MrOS). Abstract 1058]