A COMPARISON OF THE RATES AT WHICH THYROTROPHIN AND THE HUMAN ABNORMAL THYROID STIMULATOR DISAPPEAR FROM THE CIRCULATING BLOOD OF THE RAT

Abstract

Human serum, obtained from a thyrotoxic patient and containing a high concentration of the abnormal thyroid stimulator, was injected intravenously into rats. The amount of the abnormal thyroid stimulator remaining in the rats; blood after 1, 2 and 6 hours was compared with the amount present 2 minutes after injection. The half-life was 7.5 hours. Similar experiments were conducted with U. S. P. Thyrotropin Reference Substance and human pituitary thyrotrophin obtained from a euthyroid subject. One hour after injection, the level of both these preparations had fallen to less than 5% of the 2-minute level. It is suggested that the prolonged life of the abnormal thyroid stimulator in circulating blood is responsible for the prolonged nature of the response which it elicits.