3,3-Diiodothyronine (T2)

3,3'-Diiodothyronine, also known as T2, is a metabolite of thyroid hormone. It is formed from the breakdown of triiodothyronine. It is an allosteric regulator of the Cytochrome C Oxidase, the complex IV of the electron transport chain. It increases its activity by preventing the interaction of ATP as an allosteric inhibitor. ,3′-Diiodothyronine (3,3′-T2) has been detected in human serum and in thyroglobulin. However, no quantitative assessment of its clearance rate (CR), production rate (PR), or of the importance of extrathyroidal sources of 3,3′-T2 relative to direct thyroidal secretion is yet available. The production of 3,3'-T2 in NTI seems to be regulated in a disease-specific manner, resulting in unchanged, reduced, or elevated hormone concentrations. Thyroid function and 3,3'-diiodothyronine sulfate cross-reactive substance (compound W) in maternal hyperthyroidism with antithyroid treatment.