A NEW IN VITRO ASSAY FOR THYROIDSTIMULATING HORMONE

Abstract

SUMMARY: A new in vitro assay for thyroid-stimulating hormone (TSH) is described. The parameter of TSH action is the discharge of radioactive iodine from mouse thyroid glands labelled with ¹³¹I in vivo. The assay is sensitive to human TSH and gave consistent results during 1 yr. without seasonal variation. A potent preparation of long-acting thyroid stimulator gave a dose-response line parallel with human TSH. Fresh human serum was toxic to the assay preparation so that circulating TSH levels cannot be measured.