Background: Anorexia nervosa (AN) is a condition of severe undernutrition associated with low bone mineral density (BMD) in adolescent females with this disorder. Although primarily a disease in females, AN is increasingly being recognized in males. However, there are few or no data regarding BMD, bone turnover markers or their predictors in adolescent AN boys.

Hypotheses: We hypothesized that (i) BMD would be low in adolescent boys with AN compared with controls associated with a decrease in bone turnover markers, and (ii) the gonadal steroids, testosterone and estradiol, levels of insulin like growth factor-1 (IGF-1) and the appetite regulatory hormones leptin, ghrelin and PYY would predict BMD and bone turnover markers.

Methods: We assessed BMD using DXA, and measured fasting testosterone, estradiol, IGF-1, leptin, ghrelin and PYY, and a bone formation (amino-terminal propeptide of type 1 procollagen) and bone resorption (N-telopeptide of type 1 collagen) marker in 17 AN boys and 17 controls 12–19 years.

Results: Boys with AN had lower BMD and corresponding Z-scores at the spine, hip, femoral neck, trochanter, intertrochanteric region, and whole body compared with controls. Height adjusted measures (lumbar BMAD and whole body BMC/height) were also lower. Bone formation and resorption markers were reduced in AN, indicating decreased bone turnover. Testosterone and lean mass predicted BMD. IGF-1 was an important predictor of bone turnover markers.

Conclusion: AN boys have low BMD at multiple sites associated with decreased bone turnover markers at a time when bone mass accrual is critical for attainment of peak bone mass.