Free thyroxine, also called FT4, has a normal reference range of 12-22 pmol/L. If FT4 is elevated, FT3 is also elevated, and TSH is decreased, it means that the patient is hyperthyroid. At this point, you need to see an endocrinologist, who will draw thyroid-related antibodies, as well as liver function and blood work. This will then determine whether to treat with oral medication, iodine-131, or surgery. If free thyroxine is lower, FT3 is also lower, and TSH is elevated, this suggests hypothyroidism. This is also the time to see an endocrinologist, who will decide whether to replace the treatment with euthyroidism based on the results.