It is also important because it is the main source of T3,,, from
conversion. So you should insist on being tested for both FT4 and FT3 every time you go for thyroid tests.
Also, thyroid test results vary from lab to lab so you should always compare results to the lab's reference range. So we need to know that. Also, did you take your thyroid dose in the morning before the blood draw?
For symptom relief and optimizing meatabolism, you may need to add a source of T3 to your dosage.