Prevalence and clinical determinants of low bone mineral density in anorexia nervosa

Abstract

Objective To determine the prevalence of low bone mass in anorexia nervosa (AN) and the association with clinical parameters. Methods A cross-sectional study on 286 Caucasian women with AN. Bone mineral density (BMD) was measured with DXA. Low BMD was defined as a Z-score ≤ − 1.0 in at least one site (lumbar spine or femoral neck). Results A Z-score of ≤ − 1.0 in at least one of these sites was found in 46.9%. In comparison with the patients with normal BMD, in patients with a low BMD both the BMI at the time of DXA ( p = 0.005) and the lowest BMI ever ( p < 0.001) was lower. These patients also had a longer duration of AN ( p = 0.047). The decline of BMI per year between highest BMI ever and BMI at time of DXA was more rapid in subjects with a normal BMD ( p = 0.016) as compared to patients with low BMD. Low BMD was found to be independently associated with ‘lowest BMI ever’ (OR: 0.78; 95%CI = 0.66–0.93), and with ‘BMI decline per year’ (OR: 0.83; 95%CI = 0.71–0.97). Conclusion We conclude that low BMD is frequent in AN. The best indicator of low BMD appeared to be the lowest reported BMI ever.