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 <or= -1.0 in at least one site (lumbar spine or femoral neck).
Results: A Z-score of <or= -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.