[Body weight and bone/calcium metabolism. Bone and calcium metabolism in anorexia nervosa.]

Osteoporosis is one of chief complications of anorexia nervosa. Their calcium intake decreases and 84%are lack of vitamin D. The abnormal bone metabolism in severely emaciated patients with anorexia nervosa involves both a reduction in bone formation and an increase in bone resorption. The annual change in lumbar bone mineral density(BMD)is significantly correlated with body mass index(BMI)at the entry. The critical BMI for a positive increase in BMD was 16.4±0.3 kg/m2. Since 30%of patients are lack of vitamin K, their bone quality deteriorates. The risk factors of a decrease in lumbar vertebrae BMD is a duration of emaciation when both serum levels of insulin-like growth factor-Ⅰ as a potent osteogenic factor and estradiol as a powerful bone resorption inhibitor decrease. Therefore, the prevention and the treatment are weight gain. However, the patient does not accept weight gain easily. Active form vitamin D3 of 0.5μg/day or 30-45 mg/day of vitamin K2 preparation prevents the further decrease in bone mineral density. Eldecalcitol of 0.5μg/day shows about 5%increase in lumbar vertebrae BMD in first year. Bisphosphonate and a RANK ligand inhibitors, denosumab should not be used for young patients and women in hope of the pregnancy.