Lumbar bone mineral density in anorexia nervosa

We studied lumbar bone mineral densities (BMD) using a dual photon absorptiometer in 18 women with anorexia nervosa (AN). Results were compared with data from a control group of 36 healthy women. We found significantly reduced mean bone densities as compared with control group (0.814 +/- 0.072 g/cm2 hydroxy-apatite equivalent vs 1.011 +/- 0.023; p < 0.01). Only one patient developed vertebral compression fracture. BMD was negatively correlated with duration of amenorrhoea (r = -0.68; p < 0.01) but not significantly with duration of AN. We found no correlation between BMD and estradiol blood levels, age of onset, body mass index and daily calorie intake. The correlation between BMD and duration of amenorrhoea may indicate that long standing estrogen deficiency is a major factor in the osteoporosis (OP) observed in AN.