Free triiodothyronine is abbreviated as FT3. Whether the index is high or not is a serious matter, it needs to be combined with other thyroid function indexes and imaging tests to make a comprehensive judgment. If FT3 increases significantly and is accompanied by other numerical abnormalities, it suggests that the condition may be serious, and it is necessary to go to the hospital in time for medical treatment. The normal value of free triiodothyronine is 3.5-6.5 pomol/L, which is an important indicator of thyroid function. If there is only a mild increase in FT3, FT4, TSH and other thyroid function tests are normal, and the patient does not have obvious symptoms, it suggests that the patient’s condition is not serious, and regular rechecking of the thyroid function can be done. However, if FT3 increases significantly, FT4 increases and TSH decreases, it suggests that the patient may be suffering from hyperthyroidism, Hashimoto’s thyroiditis and other diseases. It is necessary to go to the hospital in time, after clarifying the cause of the disease, the use of anti-thyroid medication, such as propylthiouracil, methimazole, etc., iodine 131 treatment, surgical treatment and other ways of treatment. It is recommended that patients with abnormal values of free triiodothyronine go to the hospital in time to avoid delaying their condition.