- Reverse Tri-iodothyronine
- T3, Reverse
Reverse T3 measurement may be useful in evaluating the euthyroid sick patient with low T3 concentrations. Also useful in evaluating thyroid function and metabolism. Not to be confused with tri-iodothyronine.
Reverse T3 is derived almost completely from the peripheral monodeiodonization of thyroxine and has minimal physiological activity. T3 concentrations are elevated in acute or chronic diseases due to changes in peripheral rates of conversion of T4 to T3 and reverse T3. Several drugs such as glucocorticoids and amiodarone cause increased levels of reverse T3. Reverse T3 levels are elevated at birth and decline to normal levels by the first week of life. Measurement of reverse T3 may be of use in assessing thyroid function and metabolism in the newborn.