The five tests of thyroid function include thyroxine T4, triiodothyronine T3, free thyroxine FT4, free triiodothyronine FT3 and thyrotropin TSH. if T4 is elevated it can indicate hyperthyroidism, and elevated FT4 is more sensitive than T4 for the diagnosis of hyperthyroidism. elevated FT3 is also an indicator for the diagnosis of hyperthyroidism, and elevated T3 can indicate hyperthyroidism, but in clinical application because However, in clinical application, because T3 and T4 are significantly affected by serum thyroxine-binding globulin, free T3 and T4 are now generally used to test thyroid function. In addition, elevated thyrotropin TSH can be seen in hypothyroidism. It is the most sensitive indicator in thyroid function tests, and a decrease can be seen in hyperthyroidism.