An Improved Bioassay Method for Thyrotropic Hormone Using Thyroid Uptake of Radiophosphorus12

ARAPID, accurate, and sensitive method is needed for the bioassay of hypophyseal thyrotropic hormone (TSH). Borell, in 1945, demonstrated an increase in total phosphorus content of the thyroid gland following stimulation with TSH. This observation led Borell and Holmgren in 1949 to the use of radioactive phosphorus (P32) uptake of the thyroid of the guinea pig as an indicator of TSH activity. Later, Crooke and Matthews (1953), and Lamberg (1953), presented bioassay methods utilizing P32 uptake of the one day old chick. This report describes modifications in the radiophosphorus uptake methods which increase the accuracy and sensitivity of the assay and decrease the work required. Abstracts of this work have been reported previously (Greenspan, et al.z, 1954; Kriss and Greenspan, 1954).