FREE T3

A free T3 test, or free triiodothyronine test, measures the amount of free triiodothyronine in your blood. Triiodothyronine (T3) is a hormone produced by the thyroid gland that helps regulate metabolism and energy levels. 

A normal free T3 level is typically between 2.5–4.0 ng/dL, but reference values may vary by lab. A higher-than-normal level of T3 may indicate an overactive thyroid, while a lower-than-normal level may indicate an underactive thyroid.