No association between thyroid function and peripheral leptin, ghrelin or adiponectin levels

Hypothyroidism leads to decreased oxygen consumption yielding a decreased metabolic rate with reduced substrate catabolism and depressed appetite. Leptin is known as a regulator of appetite and weight regulation. Ghrelin stimulates growth hormone secretion as well as appetite and food intake. Moreover, recent data have shown that a reduction of adiponectin expression is associated with obesity and insulin resistance in some animal models. To explore whether peripheral leptin, ghrelin or adiponectin are involved in the regulation of appetite and body weight in hyper- or hypothyroidism, circulating levels of these hormones were measured in 115 hyperthyroid, 60 euthyroid and 15 hypothyroid consecutive patients in fasting state. There was no significant difference comparing adiponectin levels in hypo- or hyperthyroid compared to euthyroid patients. Ghrelin levels were decreased in hypothyroidism (97±55 pg/ml) compared to euthyroid patients (125±110 pg/ml), but this difference was not significant (p=0.88). Moreover, in all three study groups we detected no differences of leptin levels regarding to thyroid status. Therefore we conclude that neither in hypothyroidism nor in hyperthyroidism peripheral ghrelin, leptin and adiponectin levels play an important role in the regulation of appetite or food intake.