T3's formal name is Triiodothyronine. Free T3 levels aren't affected by protein levels so medications won't affect the testing. T3 levels are elevated in acute or chronic diseases due to changes in peripheral rates of conversion of T4 to 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.