Establishment of An Enzyme Linked Immunosorbent Assay for Free Triiodothyronine(FT3)

The methodology for determining FT3 in serum to estimate the patients with thyroidal and related diseases is established. In this new solid-phase antibody enzyme immunoassay, biotinylated T3 and HRP-streptavidin conjugate are used. The detection limit is low (0.90 pmol/L), the measurable range is 0.9 to 45.0 pmol/L, The intra- and inter-assay CVs are 3.1%~8.1% and (4.9)%~10.6%, respectively. FT3 values are obtained with this assay for 101 samples. The FT3 concentrations range is from 2.5~11.1 pmol/L in 46 euthyroid subjects, 9.7~37.3 pmol/L in 27 hyperthyroid patients, and 0.9~3.8 pmol/L in 20 hypothyroid patients and 3.4~8.5 pmol/L in 8 pregnalcy, respectively. Comparing with CIA and RIA, the clinical results correlated well. The method is suitable for clinical and research application.