Effects of chronic TSH treatment on blood sugar, serum IRI and FFA levels of thyroidectomized dogs. Glucose and insulin tolerance tests.

The effects of TSH treatment (0.1 USPU/kg body weight/die, for 3-4 days) on the blood sugar, serum IRI and circulating FFA responses to glucose and insulin were studied. Blood sugar and serum FFA levels of the dogs, in basal conditions and at any time interval during the test were slightly modified by TSH treatment. The kinetics of insulin disappearance from blood was not affected while the mean serum IRI during the insulin tolerance test was moderately reduced, which suggests that insulin space is moderately raised by TSH. The serum IRI response to glucose (OGTT, IVGTT) was found to be significantly and intensely reduced. The possibility of an inhibitory action of TSH on the insulin response to glucose in dogs, excluding the participation of the thyroid, exerted via insulin space and secretion is discussed.