BONE-MINERAL DENSITY AND MENSTRUAL IRREGULARITIES - A COMPARATIVE-STUDY ON CORTICAL AND TRABECULAR BONE STRUCTURES IN RUNNERS WITH ALLEGED NORMAL EATING BEHAVIOR

Bone mineral density (BMD), and associated biochemical and endocrine m arkers were compared in a group of runners with menstrual dysfunction (IR, n = 13), and a group of performance matched eumenorrheic runners (R, n = 15). All subjects claimed to have normal eating habits. Body h eight and weight, body mass index, and amount of body fat were similar . The IR group consisted of 5 presently oligomenorrheic (O) and 8 pres ently amenorrheic (A) runners. The BMD values of the athletes were add itionally compared with corresponding values in a reference group (C) of healthy age matched controls (n = 54). BMD values were significantl y lower in IR compared with R on all measuring sites: Total body (-9%, p = 0.03), femoral neck (-11%, p = 0.01), lumbar spine (-12%, p = 0.0 01), lower leg (-6.5%, p = 0.03) and arms (-7%, p = 0.01). In addition , IR athletes had lower total body (-5%, p = 0.01), and lumbar spine B MD (-10%, p = 0.001) than C. No differences were observed in serum IGF -1, SHBG, testosterone and cortisol, or in the biochemical marker of b one formation (osteocalcin) and bone resorption (1 CTP). Values of ser um E2, FSH and LH were low in IR and normal in R. TSH was in the norma l range in both groups, but f-T4 was significantly lower in IR than in R. The athletes were furthermore grouped according to past and presen t menstrual dysfunction severity. At all measuring sites, with the exc eption of the lower leg, increasing menstrual dysfunction severity was linearly associated with declining BMD values (p < 0.05). In conclusi on, even highly conditioned cortical bone tissue seems to be negativel y related to menstrual disorders, which may serve to explain the high incidence of stress fractures in athletes with menstrual disorders. Si ngle measurements of biochemical markers of bone resorption and format ion may not reflect the current bone status.