L-Thyroxine-13C9,15N is intended for use as an internal standard for the quantification of L-thyroxine by GC- or LC-MS. L-Thyroxine is a synthetic form of the thyroid hormone thyroxine. In vivo, L-thyroxine (0.9 and 2.7 μg) inhibits synthesis and release of thyrotropin induced by thyrotropin-releasing hormone from the anterior pituitary in mice. It also reverses decreases in levels of circulating thymic serum factor (FTS) and the number of T rosette-forming cells in an old age-induced mouse model of hypothyroidism. Formulations containing L-thyroxine have been used in the treatment of hypothyroidism.
Fenclofenac is a non-steroidal anti-inflammatory agent that competitively supresses the binding of thyroxine(T4) and triiodothyronine (T3) by thyroxine-binding globulin(TBG).
3-Iodothyronamine is derived from the deiodination and decarboxylation of endogenous thyroxine. It activates the G protein-coupled receptor known as trace amine-associated receptor 1 at nanomolar concentrations whereupon it rapidly influences thyroid hormone actions including body temperature, heart rate, and cardiac output. It has also been reported to function in controlling lipid and glucose utilization, hormonal secretion, and neuronal function, and has been considered for use in chemically-induced hibernation for medical purposes.