Predictors of low bone density in young adolescent females with anorexia nervosa and other dieting disorders

OBJECTIVE: To compare the bone density of adolescent patients with anorexia nervosa with adolescent patients with other dieting disorders and to evaluate risk factors for low bone density in these patients. METHOD: Sixty-nine consecutive female patients referred to an adolescent eating disorders clinic were studied by interview, blood sampling, body composition, and lumbar spine bone density measurement using dual energy X-ray absorptiometry. RESULTS: Although patients with anorexia nervosa were more malnourished, their bone density was similar to other dieting patients. Patients were divided into a low and normal bone density group irrespective of psychiatric diagnosis. Patients with low bone density had dieted for longer, had lower lean body mass, more often had not achieved menarche, and had longer duration of secondary amenorrhea and lower estrogen levels. DISCUSSION: Irrespective of clinical diagnosis, adolescents with dieting disorders have increased risk of low bone density when malnutrition commences early in puberty and is associated with reduced lean body mass and impaired ovarian function.