Hypothyroidism mainly refers to a series of symptoms caused by the reduced secretion of thyroid hormones, which will lead to the reduction of metabolic rate and sympathetic excitability, and a series of typical clinical symptoms will appear, mainly including low basal metabolic rate syndrome, mucous face, psychoneurological system, muscle and bone, digestive system, cardiovascular system, etc. 1. Low basal metabolic rate syndrome: fatigue, slowness of movement, drowsiness, memory loss, poor concentration, fear of cold, absence of sweat. 2. Mucous face: edema of cheeks and eyelids, pallor, cyanosis, dry hair, loss of eyelashes and eyebrows, slow growth of male beard. 3. Psychoneurological: mental retardation, tinnitus, dizziness, psychosis, dementia, numbness of hands and feet, abnormal pain sensation. 4. Muscle and bone: muscle weakness, also muscle ankylosis, spasm, joint pain. 5. Digestive system: gastric upset, anorexia, bloating, constipation, intestinal obstruction. 6. Cardiovascular system: decreased heart rate, decreased cardiac output, pericardial effusion, angina pectoris, arrhythmia. Symptoms of hypothyroidism require prompt medical observation and standardized treatment under the guidance of clinicians.