fT4(Free Thyroxine) ELISA Kit (E-EL-0122)

This ELISA kit uses the Competitive-ELISA principle. The micro ELISA plate provided in this kit has been pre-coated with Universal fT4. During the reaction, Universal fT4 in the sample or standard competes with a fixed amount of Universal fT4 on the solid phase supporter for sites on the Biotinylated Detection Ab specific to Universal fT4. Excess conjugate and unbound sample or standard are washed away, and Avidin-Horseradish Peroxidase (HRP) conjugate are added to each micro plate well and incubated. Then a TMB substrate solution is added to each well. The enzyme-substrate reaction is terminated by the addition of stop solution and the color turns from blue to yellow. The optical density (OD) is measured spectrophotometrically at a wavelength of 450 nm ± 2 nm. The concentration of Universal fT4 in tested samples can be calculated by comparing the OD of the samples to the standard curve.

Free thyroxine is a part of serum thyroxine that does not bind to binding proteins, and fT4determination is an important part of clinical routine diagnosis. fT4 and thyrotropin (TSH)are often measured together when thyroid dysfunction is suspected. fT4 is also suitablefor monitoring thyroid suppression therapy. The advantage of fT4 determination is that itis not affected by changes in its binding protein concentration and binding properties.Serum fT4 is a sensitive index of thyroid function in vitro test. When it causes changes inTBG binding force and concentration under physiological and pathological conditions, itcan reflect thyroid function more accurately, and is better than fT3 in the diagnosis ofhypothyroidism.