Hypothyroidism generally refers to hypothyroidism, a systemic hypometabolic syndrome caused by various causes of hypothyroxinemia or thyroid hormone resistance. Thyroid function tests mainly show a decrease in FT3 (free triiodothyronine), a decrease in FT4 (free thyroxine), and an increase in TSH (thyroid stimulating hormone). The normal range of these tests varies depending on the kits used in each hospital. Patients can make a preliminary judgment by the small arrows behind the values, with the upward arrow indicating an increase and the downward arrow indicating a decrease. However, the specific results should be analyzed by endocrinologists. Generally, FT3 and FT4 are normal, but TSH is elevated, which is called subclinical hypothyroidism. The endocrinologist should make a professional judgment whether treatment is needed, taking into account the patient’s symptoms, TPOAb, TGAb and TSH elevation.