Due to different congenital diseases involving the hypothalamic-pituitary-thyroid axis function, resulting in thyroid deficiency; or due to thyroid receptor defects caused by the clinical syndrome, previously known as cretinism or cretinism. I. Diagnosis (I) Clinical manifestations 1. Neonatal symptoms: the child is often born at an advanced age, with a birth weight higher than normal, prolonged physiologic jaundice, frequent abdominal distension, constipation, sleep, slow response to the outside world, poor feeding, low body temperature, and poor peripheral circulation. Typical symptoms: (1) special face and body posture: dull expression, slow reaction, mucous edema of face and body, wide eye spacing, low and flat nose root, thick lips, wide tongue, often sticking out of the mouth, bulging abdomen, umbilical hernia, short stature of the child, long torso and short limbs. (2) Other symptoms: delayed motor development, mental retardation, poor appetite, less activity, fear of cold, less response to the surrounding things, respiration, heart rate are slow, low muscle tone of the limbs, slow peristalsis, abdominal distension and constipation are common. (ii) Auxiliary examination 1, serum thyroid function measurement: TSH increased, T3, T4 decreased. 2, Bone age measurement: bone age lags behind the actual age. Isotope thyroid scan. 4.Electrocardiogram: low voltage, sinus bradycardia, prolonged P-R interval. Second, treatment 1, early, lifelong treatment: (1) thyroxine tablets: start 10-20 mg / d, can be 1-2 weeks interval gradually increase the dose once, 1-2 months or longer to 60-120 mg / d, regular measurement of thyroid function, in order to adjust the dose to the maintenance amount. (2) Levothyroxine sodium (L- T4). 2. Vitamins, minerals. (3) Regular follow-up to adjust the dose.