When triiodothyronine levels are elevated, it is necessary to determine the levels of tetraiodothyronine and thyroid-stimulating hormone to assess whether the patient has hyperthyroidism. Triiodothyronine is an iodine-containing tyrosine, mostly converted from tetraiodothyronine, that can help reflect thyroid function. If there is an increase in triiodothyronine levels, an increase in tetraiodothyronine levels and a decrease in thyroid stimulating hormone, hyperthyroidism is considered to be present and the cause of the condition needs to be clarified. If the hyperthyroidism is caused by Graves’ disease, medications and other treatments can be prescribed. If the level of triiodothyronine is increased, it is recommended to consult the endocrinology department of a regular hospital for treatment.