Understanding Diiodotyrosine: A Thyroid Hormone Metabolite and Its Clinical Significance

Diiodotyrosine (T2) is a thyroid hormone metabolite that is produced when iodothyronines (thyroxine, T4 and triiodothyronine, T3) are degraded by the liver. It is formed through the action of the enzyme thyroid hormone-degrading enzyme (THDE).

Diiodotyrosine is not an active thyroid hormone, but it can be used as a marker for thyroid hormone metabolism and excretion. Elevated levels of diiodotyrosine in the blood may indicate decreased thyroid hormone activity or impaired thyroid hormone metabolism.

It is important to note that diiodotyrosine is not a specific marker for thyroid hormone deficiency, as it can also be elevated in cases of excessive thyroid hormone intake or certain medical conditions such as hyperthyroidism. Therefore, diiodotyrosine levels should be interpreted in conjunction with other clinical and laboratory findings.