FT3, RIA CT

The radioimmunoassay of free triiodothyronine (T3) is a competition assay based on the principle of labeled antibody. Samples and calibrators are incubated with 125I-labeled monoclonal antibody specific for T3, as tracer, in tubes coated with an analog of T3 (ligand).

There is competition between the free triiodothyronine of the sample and the ligand for the binding to the labeled antibody.

After incubation, the content of tubes is aspirated and bound radioactivity is measured.

A calibration curve is established and unknown values are determined by interpolation from the curve.