Bone mineral density at extremely low weight in patients with anorexia nervosa

Objective: Low bone mineral density (BMD) is a frequent and invalidating consequence of chronic undernourishment in patients with anorexia nervosa (AN). The aim of this study was to assess prevalence and clinic-biological correlates of low BMD and fractures in extremely undernourished inpatients with AN. Design: Retrospective cohort study. Patients and measurements: This study included 97 extremely malnourished female inpatients with AN consecutively admitted over 2 years. Clinical-biological variables, history of fractures and BMD by dual-energy X-ray absorptiometry (DXA) were examined to find predictors of low BMD and fractures. Results: The prevalence of low BMD was of 51% for lumbar spine and 38% for femoral neck. Z-scores were lower at lumbar spine (-2.2 +/- 1.2 SD) than at femoral neck (-1.9 +/- 0.9 SD) (P<.01). Fragility fractures were reported by 10% of patients. BMD was mainly predicted by FFM, illness duration, age at onset and restricting AN (P<.05). Fractures were predicted by sodium concentrations, femoral neck Z-score and illness duration (P<.03). Conclusion: Extremely severe patients with AN have high prevalence of low BMD, predicted by severity and chronicity of malnutrition.