This test is used to evaluate the level of thyroid hormone thyroxine (T4) in the blood. It aids in the diagnosis of any kind of thyroid disorder. T4 plays important role in controlling heartrate, metabolism and temperature of the body. Normally, most of the T4 is found in protein bound state in the blood. Elevation of free T4 can lead to different symptoms including dry skin, sensitivity to light, increased heartbeat, irregular periods in women, unexplained weight loss or gain, gastric problems, anxiety and hair loss.
LabEspy recommends Lab Testing API, Direct Labs, Ulta Lab Tests for this test.