Thyroid Research Thyroid Research Archive Hyperthyroidism

Secretion of ghrelin, which stimulates appetite, is decreased in hyperthyroidism

(March 2003)

The background of the study. Ghrelin is a hormone produced by the stomach that acts in the brain to stimulate appetite. Many patients with hyperthyroidism lose weight and have an increase in appetite, which might be caused by increased ghrelin production. In this study, serum ghrelin was measured in patients with hyperthyroidism before and during treatment.

How the study was done. The study subjects were nine women with hyperthyroidism caused by Graves' disease and nine normal women. The women with hyperthyroidism were studied before and after treatment with an antithyroid drug, and the normal women were studied once. Serum ghrelin, leptin, insulin, and other substances were measured after an overnight fast. Body composition and energy expenditure were also measured.

The results of the study. The average weight of the women with hyperthyroidism was 59 kg before and 64 kg after treatment; the normal women weighed 70 kg. The women with hyperthyroidism had less fat tissue and a lower lean body mass than the normal women, and both values increased during antithyroid drug treatment. Their estimated energy expenditure was 52 kcal/day/kg of lean body mass before treatment and 38 kcal/day/kg of lean body mass after treatment, as compared with 34 kcal/day/kg of lean body mass in the normal women.

The mean fasting serum ghrelin concentration was lower in the women with hyperthyroidism than in the normal women (1080 vs. 1870 pg/ml); it increased (1480 pg/ml) after antithyroid drug treatment. There were no differences between the fasting serum concentrations of leptin, insulin, glucose, and fatty acids in the women with hyperthyroidism and the normal women.

The conclusions of the study. Serum concentrations of ghrelin are lower in women with hyperthyroidism than in normal women, indicating that the increase in appetite in hyperthyroidism is not caused by ghrelin.

The original article. Riis AL, Hansen TK, Moller N, Weeke J, Jorgensen JO. Hyperthyroidism is associated with suppressed circulating ghrelin levels. J Clin Endocrinol Metab 2003;88:853-7.