Measurement of free thyroid hormones in serum by column adsorption chromatography and radio-immunoassay

A new method for the assay of free thyroid hormones in human serum is described. This method is based on a chromatographic adsorption process of thyroid hormones onto a Sephadex LH-20 resin column. Protein fractions are eliminated by washing columns; adsorbed hormones are eluted with methanol and determined by radio-immunoassay. It was demonstrated that under the experimental conditions adopted the presence of the resin R does not significantly change the free hormone level in the serum, and the amount of hormone adsorbed onto the resin, HR, is exclusively a function of the free hormone concentration [H]. (Auth.)