I. Clinical manifestations of hypothyroidism Hypothyroidism is a group of diseases caused by the insufficient synthesis, secretion or biological effect of thyroid hormones due to various causes. The clinical manifestations depend on the age of onset. Hypothyroidism occurs in fetuses and infants and can lead to dwarfism and mental retardation. In adults, hypothyroidism mainly affects metabolism and organ function, and may include fear of cold, low sweating, weakness, little speech and laziness, low body temperature, loss of appetite but weight gain; memory loss, mental retardation, unresponsiveness, drowsiness; bradycardia, reduced heart sounds, sometimes pericardial effusion, etc. Patients often have muscle weakness and weakness, and occasionally myasthenia gravis. Female patients may have excessive menstruation and prolonged periods, and male patients may develop impotence. The serious symptom of hypothyroidism is mucinous edema coma, which can be life-threatening. Most patients present with goiter, and some patients have atrophy of the thyroid gland. Patients suspected of hypothyroidism should have routine blood and thyroid function (FT3, FT4, TT3, TT4) tests, as well as TSH and thyroid autoantibodies such as TGAb and TPOAb to determine the location and cause of the lesion. There are many causes of hypothyroidism, including chronic lymphocytic thyroiditis (also known as Hashimoto’s thyroiditis), hyperthyroidism after isotope treatment or surgical removal, and long-term lack of iodine in food. Hypothyroidism is usually permanent, and in some patients it is transient, such as subacute thyroiditis and inappropriate treatment with anti-thyroid medication. The doctor can clarify the cause of hypothyroidism through detailed consultation, physical examination and some tests. Treatment of hypothyroidism Once hypothyroidism is detected, thyroid hormone replacement therapy is needed. Except for transient hypothyroidism which only needs short-term replacement therapy, long-term replacement therapy is needed. Commonly used drugs include thyroid tablets and levothyroxine T4 (trade name: Eugenol). Generally, starting from a small dose (especially for the elderly), thyroid tablets or Eugenol are given half a tablet a day, and the dose is gradually adjusted after one month according to the results of the re-examination of thyroid function, with each increase of the dose not exceeding one tablet until the blood test thyroid function indexes (FT3, FT4, TT3, TT4, TSH) are completely normal, and then the treatment is maintained. The dose should not be reduced casually, and the medication should not be stopped casually, especially for women who want to get pregnant. In exceptional cases, the doctor will make adjustments to the starting dose and the rate of adjustment of the medication according to the patient’s specific situation.