Used in research settings to measure ultra-sensitive levels of thyroxine (T4) in rat serum or plasma samples. This ELISA kit enables precise detection of free T4 concentrations, supporting studies related to thyroid function, endocrine disruption, metabolic disorders, and hypothalamic-pituitary-thyroid axis regulation in rodent models. It is particularly useful in toxicology and pharmacology research where accurate monitoring of thyroid hormone changes is critical. The assay is designed for high sensitivity and specificity, allowing detection of subtle hormonal fluctuations in small sample volumes. Not intended for diagnostic or therapeutic use.