[Radioimmunoassay without extraction of L-triiodothyronine in human serum].

A radio-immunoassay of L-triiodothyronin is described. Blinding of T3 to TBG is prevented by salicylate (1%--w/v). The rabbit antiserum obtained by injection of a complexe T3-bovine serum albumin is diluted between 1/10000 and 1/20000. Bound and free hormone are separated by polyethylene glycol (17%--w/v). Serum T3-concentration in normal subjects averaged 132 +/- 29 ng/dl (SD). In hyperthyroid and hypothyroid patients, these values were respectively 351 +/- 118 ng/dl and 68 +/- 21 ng/dl.