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  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.