OSTEOPOROSIS IN WOMEN WITH ANOREXIA-NERVOSA

Because estrogen deficiency predisposes to osteoporosis, the skeletal mass of women with anorexia nervosa was assessed using direct photon absorptiometry to measure radial bone density in 18 anorectic women and 28 normal controls. The patients with anorexia had significantly reduced mean bone density as compared with the controls (0.064 .+-. 0.06 vs. 0.72 .+-. 0.04 g per cm2, P < 0.001). Vertebral compression fractures developed in 2 patients, and bone biopsy in 1 of them demonstrated osteoporosis. Bone density in the patients was not related to the estradiol level (r = 0.02). Levels of parathyroid hormone, 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were normal despite low Ca intakes. The patients with anorexia who reported a high physical activity level had a greater bone density than the patients who were less active (P < 0.01); this difference could not be accounted for by differences in age, relative weight, duration of illness, or serum estradiol levels. The bone density of physically active patients did not differ from that of active or sedentary controls. Women with anorexia nervosa have a reduced bone mass due to osteoporosis, but that a high level of physical activity may protect their skeletons.