fT4 (Free Thyroxine) ELISA Kit

Designed for the precise measurement of free thyroxine, this competitive ELISA from Assay Genie offers a sensitive and reliable tool for thyroid function research. Free thyroxine is a key hormone produced by the thyroid gland, playing a crucial role in regulating metabolism, growth, and development. Monitoring free thyroxine levels supports research into thyroid disorders such as hypothyroidism and hyperthyroidism, as well as the evaluation of thyroid function under treatment. The kit is intended for use with serum, plasma, cell culture supernatant, cell or tissue lysate, and other liquid samples, with reactivity described as Universal.

The assay is configured as a Competitive ELISA with antigen-coated wells and reports a sensitivity of 0.938 pg/mL with a working range of 1.563–100 pg/mL. Storage is at 2–8°C (sealed), with cryopreservation to be avoided. Detection is colorimetric and the standard procedure is based on a biotin-labelled antibody with TMB substrate, measured at 450 nm.

Validation data from the manufacturer includes linearity across dilution factors of 1:2, 1:4, and 1:8. Serum samples (n = 10) showed linearity of 86–101%, 87–103%, and 85–104% across the three dilutions; EDTA plasma (n = 10) gave 83–96%, 84–99%, and 85–96%; and heparin plasma (n = 10) gave 82–95%, 81–99%, and 82–99%. Spike-recovery testing reported ranges of 93–102% for serum, 88–99% for EDTA plasma, and 89–101% for heparin plasma, each with an average recovery of 95%.