Bone loss in anorexia nervosa (AN) is multifactorial; its mechanisms are not yet clearly understood and may vary depending on disease duration and severity. To determine to what extent adipokines may be involved in the bone alterations found in anorexic patients, we evaluated plasma levels for leptin, adiponectin and Pref-1 against other clinical and biological parameters in a population of anorexic patients split according to weight and bone status.

Plasma concentrations of leptin, total adiponectin, high molecular weight (HMW) adiponectin, and Pref-1 were measured. The ratio of HMW adiponectin to total adiponectin — HMW (percentage) — was calculated. We divided our population into 5 groups with different phenotypes characterizing the severity of the disease and/or the severity of bone involvement: 1 – Normal BMD and body mass index (BMI): recovery from AN; 2 – Osteopenia (−2<Z-score<−1) and BMI>17kg/m²; 3 – Osteopenia and BMI≤17kg/m²; 4 – Osteoporosis (Z-score≤−2) and BMI>17kg/m²; 5 – Osteoporosis and BMI≤17kg/m².

The study involved 80 anorexia nervosa patients. Mean BMI was 16.8±2.4kg/m². No significant difference was found in total and HMW adiponectin plasma concentrations between the 5 groups. HMW (percentage) was significantly higher in group 5 compared to group 1. Leptin was significantly lower in groups 3 and 5 compared to the other groups. For the whole group femoral neck and hip BMD correlated negatively with total adiponectin and HMW adiponectin. No correlation was found between BMD (whatever the site) and plasma leptin. Multivariate analysis revealed that 2 factors — leptin and BMI — explained 10% of the variance in spine BMD. For femoral neck BMD, the 2 explanatory factors were BMI and total adiponectin which explained 14% of the variance in BMD. For total hip BMD, 27% of the variance in BMD was explained by 3 factors: leptin, BMI, and total adiponectin.

Bone status in anorexia nervosa is mainly determined by BMI, leptin and adiponectin.