Factors involved in the regulation of plasma leptin levels in children and adolescents with anorexia nervosa

Objective: The effects of changes in body mass index (BMI) and other factors on plasma leptin levels in children and adolescents with anorexia nervose (AN) were examined. Methods: Plasma leptin levels and BMI was measured before and after initiation of refeeding therapy every 2 weeks for 8 weeks in 12 children and adolescents with AN. The plasma levels of insulin, cortisol, insulin-like growth factor-I (IGF-I), and tumor necrosis factor-alpha (TNF-alpha) were also measured in these subjects before and after 8 weeks of the refeeding therapy, and the results were compared with those from 12 age-matched healthy girls. Results: The plasma leptin and IGF-I levels, as well as the BMI, in the AN patients before refeeding therapy were significantly lower than both of these indices in the AN patients 8 weeks after initiation of the therapy and in the controls. The plasma leptin levels and BMI in the AN patients 8 weeks after initiation of the therapy were still significantly lower than those in the controls. Significant correlations between the plasma leptin levels and BMI were detected in the AN patients both before and 8 weeks after initiation of the refeeding therapy, as well as in the controls. The BMI showed a significant increase beginning at 2 weeks after initiation of the therapy compared with that before refeeding, but the plasma leptin levels did not significantly increase until 4 weeks after the initiation of therapy. Conclusion: The results suggest that plasma leptin levels reflect changes in body fat content in children and adolescents with AN, although there is a delay in the recovery of plasma leptin levels compared with those of BMI in the early period of refeeding therapy, which is probably regulated by other factors.