Comparisons of bone density and body composition among adolescents with anorexia nervosa and atypical anorexia nervosa

Objective To compare bone mineral density (BMD) and body composition among adolescents: (a) with atypical anorexia nervosa (AAN) versus anorexia nervosa (AN) and (b) those with and without a prior history of overweight. Method Electronic medical records of patients 9-20 years with AN or AAN who underwent dual-energy x-ray absorptiometry scans were retrospectively reviewed and analyzed. Results A total of 286 adolescents with AN or AAN were included. In linear regression models, AAN was associated with greater Z-scores in whole body bone mineral content (BMC, B = 0.88, p < 0.001), lumbar spine BMD (B = 0.79, p = 0.002), femoral neck BMD (B = 0.670, p = 0.009); fat mass index (B = 1.33, p = 0.003), and lean body mass index (LBMI, B = 1.10, p < 0.001) compared to AN, adjusting for age, sex, and duration of illness. A prior overweight history was associated with greater Z-scores in whole body BMC; lumbar spine BMD, total hip BMD, femoral neck BMD, and LBMI. Discussion Adolescents with AAN had higher BMD Z-scores than adolescents with AN; adolescents with a prior overweight history had greater BMD Z-scores than adolescents without a prior overweight history. These findings may inform clinical guidelines for the medical management of AAN.