General Free Thyroxine ELISA Kit

This competitive immunoassay from Antibodies.com quantifies free thyroxine (fT4), the unbound fraction of the principal thyroid hormone that governs cellular metabolic rate. Because circulating fT4 is not bound to carrier proteins such as thyroxine-binding globulin, transthyretin, or albumin, it reflects the biologically active pool more accurately than total T4 measurements, and the kit supports thyroid-axis characterization, reproductive endocrinology studies, and metabolic-disorder research.

The 48-well microplate format uses a competitive binding strategy appropriate for small hapten analytes like thyroxine. Calibrators and samples are co-incubated with HRP-labeled T4 conjugate, where signal intensity is inversely proportional to free thyroxine concentration. The kit delivers a detection range of 0.5 to 30 pg/mL and a sensitivity around 0.1 pg/mL, run with a 50 uL sample volume. Researchers apply this assay to serum specimens drawn under standard collection protocols, supporting biomarker screening, pharmacological response studies, and longitudinal monitoring of thyroid-related parameters.

Each pack contains a pre-coated 48-well microplate strip, lyophilized calibration standards, HRP-T4 conjugate, wash buffer concentrate, TMB substrate solution, and stop reagent sufficient for 48 individual determinations. Reconstituted reagents should be kept refrigerated and protected from light until first use. Lot-specific performance data and a complete printed protocol are included with the order, and the printed shelf life supports standard laboratory turnover.