Methods for labelling triiodo thyroxin (T3) and L-thyroxin (T4) with I-125 used in radioimmunoassay

A rapid and sensitive radioimmunoassay has been developed for the measurement of T3 and T4 in human serum. This method is particularly useful for evaluating hyperthyroidism and hypothyroidism in patient with thyroid disease. T3 and T4 has been labelled with I-125 using chloramin-T method to attain tracers with specific activity 2500-3000μCi/μg. Iodinated products have radiochemical purity more than 98% (by paper electrophoresis of purified pooled fraction), immunoreactivity above 70%, non specific binding (NSB) less than 10%, used as tracer in RIA. (author)