The FT4 (Free Thyroxine) Test measures the level of free thyroxine, a thyroid hormone that is not bound to proteins in the blood. This test is essential for evaluating thyroid function and diagnosing disorders such as hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid), as free thyroxine plays a crucial role in regulating metabolism, energy levels, and overall health. The test involves drawing a blood sample, which is then analyzed in a laboratory to determine the concentration of free thyroxine.

Typically, the FT4 test is performed once if there is a suspicion of thyroid dysfunction. If you are undergoing treatment or monitoring a thyroid condition, your healthcare provider may recommend repeating the test periodically. Depending on the results, follow-up tests or additional thyroid function assessments, such as TSH, may also be suggested by your healthcare provider.