Serum T3 may be assayed by the same technique as T4-RIA. Total serum T3 (T3-RIA) is a specific, direct measurement of T3 using anti-T3antibody and should not be confused with the test formerly called the T3U. As previously mentioned, the T3U (THBR) is primarily an estimate of serum protein unsaturated binding sites, which secondarily provides […]