Thyroid hormones affect plasma ghrelin and obestatin levels.

Using radioimmunoassay, the effects of thyroid hormones on plasma total ghrelin (Gh) and obestatin (Ob) concentrations were evaluated in thyrotoxic patients with an excess of thyroid hormones and in hypothyroid patients lacking endogenous thyroid hormones. 24 patients with thyrotoxicosis, 25 hypothyroid patents after total thyreoidectomy performed due to thyroid cancer, and 17 control subjects were examined. Compared with the controls, the ghrelin and obestatin were elevated in hypothyroidism, while they were decreased in thyrotoxicosis. The plasma Gh and Ob levels differ depending on the thyroid function. In thyroid hormones deficiency, plasma Gh and Ob are increased, while in patients with excess of thyroid hormones, the levels of both Gh and Ob are definitely lower. Gh/Ob ratio is higher in hypothyroidism than in control subjects and thyrotoxic patients.