3-Iodothyronamine (T1AM): A New Player on the Thyroid Endocrine Team?

3-Iodothyronamine (T1AM) is an endogenous compound with chemical features that are similar to thyroid hormone. T1AM has a carbon skeleton identical to that of T4 and contains a single carbon-iodine bond. Theoretically, T1AM could be produced from T4 by enzymatic decarboxylation and deiodination. Recent studies show that T1AM and higher iodinated thyronamines are subject to similar metabolic processing as iodothyronines such as T4, suggesting a biological linkage between iodothyronines and iodothyronamines. In addition, single doses of T1AM administered to rodents induce a hypometabolic state that in certain ways resembles hibernation and is opposite to the effects of excess T4. This review will discuss the latest developments on this recently discovered thyroid hormone derivative. 3-Iodothyronamine is a biologically active, endogenous derivative of thyroid hormone that may represent a new arm of the thyroid endocrine system.