Changes in bone turnover in patients with anorexia nervosa during eleven weeks of inpatient dietary treatment.

BACKGROUND

Many adolescents with anorexia nervosa suffer from severe osteopenia and osteoporosis. We hypothesized that individualized nutrition therapy may improve bone turnover in anorectic patients.

METHODS

We studied 19 female patients [mean age, 14.2 +/- 1.4 years; mean body weight, 39.3 +/- 5.4 kg; mean body mass index (BMI), 14.2 +/- 1.4 kg/m(2)] with anorexia nervosa (International Classification of Diseases-10: F50.0, F50.1) for a period of 3 months. Nutrition therapy began at the end of the first week and included individualized hypercaloric diets, high calcium intake (2000 mg/day), and administration of vitamin D (400 IU/day). Blood samples were taken at baseline and again in weeks 3, 7, and 11. We measured serum calcium, parathyroid hormone, bone formation and resorption markers, insulin-like growth factor 1 (IGF-1), and leptin.

RESULTS

Mean BMI increased significantly, from 14.2 +/- 1.4 to 17.1 +/- 0.7 kg/m(2) (P = 0.000001), during the course of treatment, whereas serum total calcium and phosphate concentrations remained unchanged. The bone formation markers procollagen-I carboxy-terminal propeptide and bone alkaline phosphatase almost doubled (P = 0.006). Both IGF-1 (P = 0.00001) and leptin (P = 0.000005) increased significantly by week 11. Parallel to this, the serum concentration of C-telopeptide, a bone resorption marker, decreased significantly (P = 0.009).

CONCLUSIONS

Nutritional rehabilitation, possibly as a result of increasing IGF-1 and leptin concentrations, may increase bone formation. It therefore provides additional objective evidence of the importance of nutrition for bone.