Bone mineral density in male adolescents with anorexia nervosa

To determine the percentage of male adolescent patients with abnormal bone mineral density (BMD), to identify the variables related to BMD loss, and to study BMD change after follow-up.

Dual-energy-x-ray absorptiometry tests at the lumbar spine (L2-L4) and the femoral neck were administered in 20 male adolescents with anorexia nervosa (treated from 1997 until 2000 at the Department of Child and Adolescent Psychiatry and Psychology of the Hospital Clinic Universitari in Barcelona). Examinations were repeated in 15 patients after a follow-up of 6 to 24 months.

Thirty-five percent of patients had osteopenia at the lumbar spine and femoral neck. The following variables were related to osteopenia: >12 months' duration of anorexia (p = .003), <3 hours/week of physical activity (p = .009), and calcium intake <600 mg/day (p = .015). In a stepwise logistic regression analysis to predict spinal BMD with the three variables mentioned above, only months of duration entered in the equation (beta = 3.5, SE = 1.3, p = .008) and correctly classified 85% of patients. At the follow-up, patients with only partial weight recovery had a BMD loss of 3.2% at lumbar spine and 6.4% at femoral neck, whereas patients with total weight recovery had an increase of 7.8% at lumbar spine and 6.7% at femoral neck.

The risk of osteopenia in male adolescents with anorexia of more than 12 months' duration is high. In patients with total weight recovery, BMD increase is higher than normal.