Interaction between serum leptin levels and hypothalamo-hypophyseal-thyroid axis in patients with anorexia nervosa.

The main objective of the study was to evaluate the endocrinological picture of anorexia. Serum leptin levels are low in untreated anorexia nervosa (AN), but studies of the exact relationship between leptin, body weight and hormones of hypothalamo-hypophyseal-thyroid axis and the impact of refeeding in anorectics are limited. The sample consistent of 15 patients with anorexia nervosa before and 1 mounth after partial weight recovery, and 15 age-matched control subjects. The body mass index (BMI), leptin, plasma neuropeptide Y (NPY), serotonin, thyroxine (T-4), triiodothyronine (T-3) and reverse triiodothyronine (rT(3)) in serum were evaluated for each subject. The mean serum levels of leptin, T-4, and T3 were significantly lower before weight recovery in 15 patients with AN than they were in control subjects. After partial weight recovery, basal T-3 levels were unchanged and significantly lower than in controls. Basal T-4 was even still more reduced, but we observed significantly elevated ratio of T-3/T-4 and reduced ratio rT(3)/T-4 Of in AN patients after gain recovery, indicating increased conversion of T-4 to T-3 than to rT(3). The levels of serum leptin were low in AN, but after partial weight recovery slightly increased, and correlated with BMI. No differences were observed in serum NPY. Serum levels of IGF-1 and serotonin were lower in AN than in controls before and after partial weight gain. IGF-1 was slightly increased after partial weight gain.