The most common tests in the general thyroid function test are total T3 and total T4, as well as free T3, free T4, TSH, TPO-Ab and TG-Ab. Generally, free T3 and total T3 are the same, and free T4 and total T4 are the same, and if both T3 and T4 are elevated, in most cases TSH is decreased and they are in opposite directions. If the direction is the same, for example, T3 is elevated, T4 is elevated, and TSH is also elevated, we should suspect the presence of pituitary disease, and also look at TPO-Ab and TG-Ab. If these two antibodies are positive or the values are high, we should suspect the presence of chronic thyroiditis.