Evaluation of a rapid and simple technique for the radioimmunoassay of triiodothyronine (T3).

This report compares T3 measurements obtained on the same serum samples by a resinstrip technique and by another existing radioimmunoassay method. The samples analyzed were obtained from a total of 90 subjects who were clinically categorized as hypothyroid, normal, hyperthyroid, or euthyroid while taking estrogen-containing compounds or while pregnant. The correlation coefficient for all 90 sera with these two different techniques was 0.94. All subjects who were clinically euthyroid (32) had a normal serum T3 concentration by the resin-strip technique. Similarly, 23 clinically hyperthyroid patients had elevated serum T3 concentrations and 15 of 17 clinically hypothyroid patients had decreased serum T3 levels.