A reproducible estimation of triiodothyronine uptake

A simple method for the determination of triodothyronine (T3) uptake using I125-T3 and dextran coated charcoal is described. This reaction is time dependent after the addition of dextran coated charcoal. Effect of temperature, concentrations of I125-T3 and charcoal are reported. Within-run precision has been estimated for normal (CV 4.2%), high (CV 2.7%) and low (CV 6.6%) ranges. Day-to-day precision was similar to within-run precision. Results obtained by this method highly correlate with those obtained using Thyopac-3 reagent kit (Amersham-Searle Laboratories).