Measures the total amount of thyroxine (t4) that is being produced by the thyroid gland.
T4 (thyroxine) is one of two hormones produced by the pituitary that helps the body regulate energy, the other being T3 (triiodothyronine). This test measures the total amount of T4 being produced. High levels of T4 may indicate hyperthyroidism (overactive thyroid) and low results may indicate hypothyroidism (underactive thyroid).
Recommended with T4 Total
Is Fasting Required? No
More Information: http://www.questdiagnostics.com/testcenter/TestDetail.action?ntc=867