Bone mineral density in anorexia nervosa: Only weight and menses recovery?

The study objectives were to analyze the presence of reduced bone mass in a sample of patients with anorexia nervosa (AN) and amenorrhea, to assess Bone Mineral Density (BMD) recovery after having a normal weight is reached and regular menses are resumed, and to predict BMD after a treatment period considering different variables (baseline BMD, baseline and final body mass index (BMI), treatment duration).

35 patients with AN (mean age 20.57±5.77) were studied at treatment start (T₀) and after they had recovered their normal weight and regular menses (T₁) in order to measure their BMD using quantitative computed tomography (QCT) of the lumbar spine (L2-L4).

At T₀, 2.86% of patients had normal BMD, while a reduced bone mass consistent with osteopenia or with osteoporosis was found in 22.86% and 74.28% of patients respectively. At T₁, the percentages were 20%, 20%, and 60% respectively. No significant differences were seen in L2-L3 and mean BMD (L2-L4). A significant difference was however found for L4 (p<0.05). A positive relationship was seen between final body mass index (BMI) and final BMD in patients with T₀-T₁>11 months, but not when the time period was ≤11 months.

This follow-up study of changes not only in BMD but also in BMI and recovery of menses has clinical relevance from the viewpoint of the day-by-day treatment process. Use of QCT makes the study more relevant because this is a more advanced technique that allows for differentiating trabecular and cortical bone.