T4 Recombinant mAb (SDT-5957)

Thyroxine (T4) constitutes the principal secretory product of the thyroid follicular cells, distinguished by its four iodine atoms. It functions primarily as a pro-hormone, serving as a stable circulating precursor that is converted peripherally into the more potent Triiodothyronine (T3) via deiodinase enzymes. Due to its longer half-life (approximately 7 days) compared to T3, T4 provides a stable index of thyroid status. Diagnostically, the measurement of Free T4 (FT4) is indispensable because it is not influenced by fluctuations in thyroid-binding proteins (such as albumin or thyroxine-binding globulin), which can alter Total T4 levels without affecting metabolic status. While TSH is the most sensitive screening test for thyroid dysfunction, T4 quantification is required to confirm the diagnosis, determine the severity of the disease, and distinguish between primary thyroid failure and central pituitary disorders. Consequently, T4 remains a fundamental parameter in the endocrine evaluation of metabolic health.