| Abstract: | Specific method for accurate radioimmunoassay of free and total thyroxine in un-extracted serum has been developed. The method is used for estimation of either free thyroxine (T4) or total T4 by inhibition of the binding sites of T4 to protein using TCA/NaOH mixture. The antibodies used in this study were obtained from Mallinkrodt. The separation technique used in our modification is that of dextran charcoal, this is to absorb the free fractions on charcoal. The kinetics of antibody antigen combination, the parameters of the experiment like; charcoal concentration, antibody dilution, temp., time of incubation and radioactivity concentration were, studied to optimize the standard curve and the sensitivity of T4RIA. Serum samples of different thyroid cases were investigated for determination of free and total T4 concentration to get the levels for each group of which 50 normals, 57 hyperthyroidism and 21 hypothyroidism in comparison with the classical tests of thyroid functions. Also sensitivity and variance coefficient has been carried out in comparison with other T4RIA techniques. |
