Follow-up of bone mineral density and body composition in adolescents with restrictive anorexia nervosa: role of dual-energy X-ray absorptiometry

BACKGROUND/OBJECTIVES: Restrictive Anorexia nervosa (ANR) is an eating disorder (ED) characterized by a low bone mineral content (BMC) and by an alteration in body composition (reduction and abnormal distribution of fat mass—FM and lean mass—LM). The aim of our study was to address whether bone and body composition changes could be influenced by hormonal status and sport in female adolescents with restrictive anorexia nervosa-ANR. SUBJECTS/METHODS: Prospective study on 79 adolescents with ANR submitted to Dual Energy X-Ray Absorptiometry—DXA at baseline-T0 and after 12 months-T12. Among the 46/79—58.2% patients that completed the study, we evaluated total and regional FM and LM%, as well as lumbar bone mineral density (BMD) and Z-score, linking them to clinical variables: menarche/amenorrhea/ hormonal therapy and physical activity. RESULTS: At T0: body mass index (BMI)¼16.4±1.4 kg/m2 with low levels of FM% (21.7±5.7) low BMC in 12/46—26.0% (mean Z-score: 1.21±1.27, with higher values related to physical activity—P¼0.001). At T12: a significant increase in BMI—P¼0.001, with LM reduction and FM increase (more evident in the trunk—Po0.001); regarding bone, no significant changes were observed, though a tendency in terms of improvement associated with resumption of menses. CONCLUSIONS: After 1 year, weight recovery was not associated with a reestablishment of bone values; by contrast, it was associated with an increase and a distortion in FM distribution, more evident in trunk region (potential and adjunctive risk factor for the relapse of the psychiatric condition). The complexity of these clinical findings suggested DXA, a low-dose and low-cost technique, in long-term monitoring of ANR patients.