[Triiodothyronine thyrotoxicosis in nodular toxic goiter]

Serum protein-bound iodine (PBI), total blood thyrotoxin (T4), triiodthyronine (T3), coefficient of thyrotoxin efficacy (CTE), serum thyrotoxin-binding capacity (TBC) or some of these indices were determined in 44 patients with nodular toxic goiter with thyrotoxemia. An increase in T3 level was revealed in 27 of 35 of the patients; T3-thyrotoxicosis was diagnosed in 18 of these in whom an increase of the T3 level was combined with normal T4 or normal CTE content and an unchanged TBC. The symptoms of T3-thyrotoxicosis displayed no significant differences from the symptoms of thyrotoxicosis caused by the excess of thyroxin. In many of the patients T3-thyrotoxicosis coursed for a long time with but a few symptoms. Loss of weight in this form of thyrotoxicosis was much less frequent than in "thyrotoxin'' thyrotoxicosis. PBI was elevated in 12 of 44 patients, and total T4 and CTE -- in 10 of 35. These methods do not permit to diagnose hyperthyroidism in many of the patients with nodular toxic goiter in which T3-thyrotoxicosis is of frequent occurrence.