Objectives: To determine which variables are associated with a significant
reduction in bone mineral density (BMD) in adolescent anorexia nervosa and
to establish guidelines for indication of bone densitometry. Method: One hu
ndred seventy patients (treated from 1997 until 1999), aged 10 to 17 years,
with a DSM-IV diagnosis of anorexia nervosa were evaluated by dual-energy-
x-ray absorptiometry in the lumbar spine (L2-L4) and the femoral neck. The
results were compared with the normative data for BMD values by age and sex
in Spanish adolescents. Results: 44.1% of patients had osteopenia at the l
umbar spine and 24.7% at the femoral neck. The following variables were rel
ated to osteopenia: more than 12 months since onset of the disorder (p < .0
01), more than 6 months of amenorrhea (p < .001), body mass index <15 (p <
.001), calcium intake <600 mg/day (p < .01), and <3 hours/week of physical
activity (p < .001). In a stepwise logistic regression analysis to predict
reduced spinal BMD, 3 variables-months elapsed since the onset of weight lo
ss, calcium intake, and body mass index-correctly classified 78.8% of patie
nts. Conclusions: Adolescent anorexia nervosa patients with the characteris
tics outlined above are at high risk of reduced BMD, and densitometry is re
commended to determine the degree of osteopenia.