THE PRESENCE OF AN ABNORMAL THYROIDSTIMULATING HORMONE IN THE SERUM OF SOME THYROTOXIC PATIENTS*

Abstract

Pituitary extracts and sera from a variety of animal and human subjects have been tested for thyroid-stimulating hormone (TSH) activity, by measurement of their effect in raising the, plasma I¹³¹ level in thyroxine-treated guinea pigs. Sera from some cases of thyrotoxicosis elicit abnormal TSH responses. The abnormality consists of a marked prolongation of the time course of the response. When U.S.P. Thyrotropin Reference Substance is added to a serum which elicits the abnormal TSH response, the magnitude and time course of the response induced by the mixture indicate that the two components act independently. It is suggested that sera eliciting the abnormal response contain an abnormal form of TSH. This material, which has so far been found only in sera from thyrotoxic patients, may have some relationship to the hyperthyroidism and possibly also to the exophthalmos of thyrotoxicosis.