Not all labs use the new range for TSH, so even if you''re in the lab's normal
range, it still might not be normal
Free T3 and Free T4 are the actual thyroid hormones, with Free T3 being the one the correlates with symptoms. Many doctors believe that TSH is all that needs to be tested, and they are wrong. Thyroid hormones control metabolism, body temperature, heart rate and other body functions.