Hypothyroidism, short for hypothyroidism, is a syndrome caused by insufficient synthesis, secretion or biological effect of thyroid hormones. It is characterized by a decrease in the body’s metabolic rate and, in severe cases, by the development of mucinous edema. It is common for hypothyroid patients to feel easily tired. History and symptoms: The onset of the disease is slow, with early weakness, fatigue, weight gain, and inability to tolerate cold. The following are drowsiness, slow reaction, low and coarse voice, facial swelling, dry skin, hair loss, abdominal distension, constipation, yellow face, decreased libido, sterility/infertility, menstrual disorders, etc. Physical examination: rough skin, mucous edema of different degrees, obvious in both lower limbs, anemic appearance, fat tongue, hoarseness, enlarged thyroid gland, slow heart rate, enlarged heart, pericardial effusion in severe cases, even pleural and abdominal effusion. The TSH is elevated in primary hypothyroidism, while the TSH is not elevated in pituitary hypothyroidism or hypothalamic hypothyroidism, The TSH and TRH excitation tests help to differentiate between primary, pituitary and hypothalamic hypothyroidism, and blood cholesterol and triglycerides are often elevated. 2. Thyroid iodine uptake is reduced; thyroxine is increased in patients with thyroid receptor resistance, but hypothyroid symptoms are still present. 3.Electrocardiogram shows sinus bradycardia. 4.X-ray chest film shows enlarged heart shadow, and some of them may have pleural effusion.