EFFECT OF THYROTROPIN ON THE SERUM PROTEIN-BOUND IODINE LEVEL IN VARIOUS THYROID STATES (TSH-PBI TEST)*

Abstract

Single intramuscular injections of thyroid-stimulating hormone (TSH) were given to 22 normal subjects and to 67 patients with abnormal thyroid or anterior pituitary glands. Resulting changes in serum protein-bound iodine (PBI) concentration were measured. Among the normal subjects PBI concentrations had risen to maximal heights by the fifteenth hour after injection when the dose was 10 I.U. and by about the twentieth hour when the dose was 20 I.U. In both cases maximal elevations of PBI concentration were maintained beyond the twenty-fourth hour. Twenty-four hours after injection of 5, 10 or 20 I.U., the mean rises in PBI concentration for the normal subjects were 1.3 μg. ± 0.6 (s.d.), 2.2 μg. ± 0.6, and 2.8 μg. ± 1.0 per 100 ml., respectively. Among the patients, determination of rises in PBI concentration twenty-four hours after injection of 10 I.U. revealed that, with exceptions, responses were abnormally low in patients with diffuse thyroid disease whereas they were normal in patients with focal thyro...