Bone Density at Multiple Skeletal Sites in Amenorrheic Athletes

Objective: To determine if there is a generalized loss of bone mass at multiple skeletal sites in amenorrheic athletes compared with a group of eumenorrheic athletes.

Design: A case-control study examining the differences in bone mineral density (BMD) between amenorrheic and eumenorrheic athletes.

Setting: Seattle, Wash, and surrounding communities.

Participants: Forty-nine athletes, aged 17 to 39 years, were selected from those responding to advertisements in local sporting-goods stores and a track-and-field newsletter. Athletes were defined as amenorrheic if they had had fewer than 2 menstrual cycles in the last 12 months or none in the past 6 months, or eumenorrheic if they had had 10 to 13 cycles in the previous year. Only women who met these criteria, confirmed by tests for estradiol and progesterone levels, were enrolled in the study.

Main Outcome Measures: Bone mineral density measured by dual-energy x-ray absorptiometry.

Results: Amenorrheic athletes had significantly lower BMD (P < .01) at the lumbar spine, femoral neck, trochanter, Ward triangle, intertrochanteric region, femoral shaft, and tibia. No difference was noted at the fibula. Body weight combined with months of amenorrhea and age of menarche predicted the BMD of the lumbar spine for amenorrheic athletes. Duration of amenorrhea and body weight of amenorrheic athletes predicted BMD at the femoral neck, trochanter, intertrochanteric region, and tibia. Weight alone predicted BMD at the femoral shaft and tibia. Age plus weight predicted lumbar BMD of eumenorrheic women.

Conclusion: Extended periods of amenorrhea may result in low bone density at multiple skeletal sites including those subjected to impact loading during exercise.