Hypothyroidism (hypothyroidism) is a clinical syndrome in which the metabolic activity of the body decreases due to insufficient synthesis, secretion or biological effect of thyroid hormones caused by various reasons. Hypothyroidism occurs mainly after surgical removal of the thyroid gland, after isotope therapy or after anti-thyroid medication, etc. Also, thyroid function itself gradually decreases with age. Of course, normal adults do not have symptoms of hypothyroidism. The clinical manifestations of hypothyroidism are mainly the following: 1. hypometabolic syndrome: fear of cold, no sweating, body temperature lower than normal, rough skin, hair loss, fatigue, slow movement, drowsiness, significant memory loss, and inattention. 2. Mental and neurological symptoms: mental retardation, drowsiness, decreased comprehension and memory. Visual, auditory, tactile and olfactory sensations are dull, accompanied by tinnitus and dizziness. Sometimes it may be neurotic or may occur delusions, hallucinations, depression or paranoia. In severe cases, there may be mental disorders, such as wood stiffness, dementia, and lethargy. 3. Cardiovascular manifestations: slow pulse, bradycardia, low heart sound, etc. Occasionally, there is pain or pressure in the precordial region. 4.Digestive system: mainly loss of appetite, constipation, abdominal distension and weight gain, etc. 5. Musculoskeletal system: pain in the limbs, shoulder and back muscles and joints, self-conscious stiffness, and less flexibility in fine hand movements than before. The numbness of hands and feet at rest can disappear after activity. 6. Reproductive system: increased or disrupted menstruation in women, some patients may have overflowing breast; male impotence. Both sexes have decreased libido. 7, thyroid symptoms: the neck is generally no obvious abnormalities, and those with a previous history of hyperthyroidism feel a significant reduction in the neck. 8. Eye symptoms: dry eyes, few tears; most patients have puffy eyelids. 9. Other: there may be anemia and swelling of the lower limbs, etc.