AN IMPROVED BIOASSAY METHOD FOR THYROTROPIC HORMONE USING THYROID UPTAKE OF RADIOPHOSPHORUS12

Abstract

A method was developed for the bioassay of thyrotropic hormone (TSH) which utilizes the uptake of P32 by the thyroid of the one day old cockerel 6 hours after the intracardiac injection of TSH. Sta-tistical analysis indicates that the response metameter, the square root of T, where T equals the time to count 1024 counts per thyroid, yields both linearity of response and homogeneous variance. Standard statistical analysis can therefore be applied to the bioassay of purified TSH in the dose range of 0.00025 to 0.005 USP units of TSH with a degree of precision indicated by a pooled lambda of 0.34. Preliminary studies have indicated the presence of modified TSH activity in the residue of an ultra-filtrate of normal human urine.