Preparation of 125 I-thyioxine and 125 I-triiodothyronine of High Specific Activity for the Radioimmunoassay of Serum Total T4 and T3

Abstract

A simple and inexpensive procedure for the preparation of high specific activity ¹²⁵I radioiodinated triiodothyronine and thyroxine is described. The specific activities achieved are approximately 350 Ci/g for ¹²⁵I-T4, and either 220 Ci/g or 500 Ci/g for ¹²⁵I-T3 depending on the reagents employed. The high specific activity ¹²⁵I-T4 and ¹²⁵I-T3 are suitable for the routine radioimmunoassay of serum total T3 and T4. When properly stored they have a shelf life of at least seven weeks.