[Direct radioimmunologic determination of T 3 in the serum]

A convenient, precise and repeatable radioimmunological method has been developed for measuring triodotironine (T3) in the serum. The dosage is made in the presence of 600 mug (micrograms) of Merthiolate in all tubes, in order to inhibit a link between the T3 and the vector proteins, and of HSA in the standards to keep them in the same condition as the samples. The method normally distinguishes 10 pg of T3 which correspond to a concentration of 0.4 ng/ml, from the point in which 25 mul of the serum are utilized. The following results have been obtained by this method: hypothyroids (14): 0.37 +/- 0.31 ng/ml; normal thyroids (51): 1.44 +/- 0.52 ng/ml; hyperthyroids (22); 4.62 +/- 1.21 ng/ml.