Abstract
A new procedure for radioimmunoassay (RIA) was applied to determine the serum concentration of thyroxine (T4). Mixtures of T4-methylester hydrochloride-bovine serum albumin complex and complete Freund's adjuvant were injected to rabbits to get them immunized. Specific anti- T4 rabbit serum, high in titer, could be obtained 18 months after the start of immunization. RIA for T4 extracted by ethanol from serum was performed by an application of dextran-coated charcoal to separate bound and free 125I-T4. On the other hand, RIA for T4 performed directly in the serum containing 100 mg/ 100 ml of 8-anilino-l-naphthalene-sulfonic acid (ANS) gave a similar standard curve for T4 obtained by the ethanol-extraction method. Serum T, values obtained by the methanol-extraction method were 9.7±3.3, μg/100 ml for normal subjects, 17.8±2.9μg/100 ml for patients with hyperthyroidism and 0.6±0.3 μg/100 ml for those with hypothyroidism. The corresponding figures obtained by RIA in the serum containing ANS were 11.1±2.1, 19.1±3.3 and 0.7±0.7 μg/100ml, respectively. The figures positively correlated respectively to the serum T4. values obtained by the competitive protein-binding analysis method (Tetrasrob-125)
