[In vitro diagnosis of T3 thyrotoxicosis]

A study was made of the importance of various radioimmunoassays and their reliability in the diagnosis of functional activity of the thyroid parenchyma in patients with nodular goiter. A total of 298 patients were examined, of them 172 with nodular toxic goiter and 116 with nodular euthyroid goiter. During scanning the most frequent variant of nodular goiter was a "warm" or "hot" node, then a "cold" and "autonomous" one. To define the effect of the globulin thyroxine binding ability on the level of general serum triiodothyronine (T3), the index of triiodothyronine and the index of elevated serum triiodothyronine (IEST3) were calculated. A comprehensive procedure of test registration reflecting hypophyseal-thyroid function was used to reveal 3 types of thyrotoxicoses: T3/4-thyrotoxicosis, T3-thyrotoxicosis and T4-thyrotoxicosis. A high informative value of the main tests--the determination of the content of general thyroxine (T4), T3 and effective thyroxine factor--was established. The IEST3 is of the utmost diagnostic value, particularly in diagnosing T3-thyrotoxicosis.