Laboratory tests can measure either total amount of hormone (bound plus unbound) or just the free portion. The free T4 test is thought by many to be a more accurate reflection of thyroid hormone function and, in most cases, its use has replaced that of the total T4 test. However, some professional guidelines still recommend the total T3 test so either free T3 or total T3 may be ordered by a health practitioner.
- Immunoassay (IA)
- For diagnosis of hypothyroidism and hyperthyroidism.
- Thyroid Function Panel, T3, T4, Thyroxine