[Homologous radioimmunoanalysis of serum L-thyroxine and triiodo-L-thyronine in rats with hypo- and hyperthyroidism].

Total L-thyroxine and triiodo-L-thyronine serum concentrations have been measured in 70-day-old male rats under normal conditions (controls) and in rats subjected to several experimental alterations of the thyroid function: hyperthyroidism, hypothyroidism and substitutive treatments. Since some problems appear when standard curves are performed with hormone serum, as consequence of differences in the affinity and inhibitory effects between heterologous proteins at the antigen-antibody reaction, RIA in this work has been carried out with standard curves performed with rat serum maintaining similar protein concentrations in standard and problems. This modification avoids errors by the use of extraction methods and shows a high degree of similarity between standard and problems.