May be a useful test in evaluating euthyroid sick patients with low T3 levels.
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 T4 to T3 and reverse T3.
Increased levels associated with glucocorticoids and amiodarone.
Levels are elevated at birth and decline to normal levels by the first week of life.