Irreversible bone loss in former amenorrheic athletes.

Small gains in bone mineral density (BMD) have been reported in the first year following resumption of menses in amenorrheic athletes but there have been no long-term outcome studies. The purpose of this study was to determine whether the BMD of former oligomenorrheic or amenorrheic athletes normalizes following several years of normal menses or use of oral contraceptives. Twenty-nine athletes first studied in this laboratory 8.1 years (range 6-10 years) ago were available for follow-up. At recruitment (time 1) 29 athletes, mean age of 30.6 years, were non-smokers, exercised 4 or more days/week for at least 45 min, had not used oral contraceptives, and had no medical conditions affecting bone metabolism. At time 1, 9 women (R/R) had always menstruated regularly, 9 (R/O/A) had experienced intermittent oligo/amenorrhea as well as regular menses, and 11 (O/A) had never menstruated regularly. At follow-up (time 2) mean age of the women was 38.2 years and there were no significant changes in height, weight or activity patterns. BMD (g/cm2) was measured at the lumbar vertebrae (L1-4 and femoral neck by dual-energy X-ray absorptiometry and expressed as a percentage of R/R values. Vertebral BMD was significantly lower in the O/A group compared with the R/R group at both time 1 and time 2 (p < 0.05). The R/O/A group had intermediate values and did not differ significantly from R/R or O/A at either time. Differences in technique between machines for determining femoral neck BMD made it difficult to detect the longitudinal effect of menstrual status at that site. Despite several years of normal menses or use of oral contraceptives, the mean vertebral BMD of former oligo-amenorrheic athletes remained low, being 84.4% of the R/R value compared to 84.8% at time 1. Those experiencing menstrual regularity with intermittent oligo/amenorrhea remained at an intermediate position of 94.7% of the R/R mean. Our results suggest early intervention is necessary to prevent irreversible vertebral bone loss in oligo/amenorrheic athletes.