Thyroxine (T4), Free, Direct (Free T4) LabCorp
This test measures the total amount of thyroid hormone T4 (thyroxine) in the blood, which can help identify a thyroid disorder.
LabCorp Test #: 001974, CPT: 84439
What is this test?
This test can detect abnormal T4 levels, which can help diagnose thyroid disease. Many providers consider the Free T4 test be more sensitive in detecting thyroid hormone production. T4 is produced by the thyroid and then bonds to proteins before it is converted to T3 in the tissues.
Who is this test for?
The Free T4 test is for anyone who wants to screen for thyroid conditions. Symptoms related to elevated T4 levels include anxiety, insomnia, diarrhea, and muscle aches and pains. If you are experiencing these symptoms, a T4 test can help determine whether they are caused by thyroid disease.
