When infants develop hypothyroidism, the timing of the review is mainly related to the course of the disease. At the beginning of treatment, thyroid function needs to be closely checked in order to adjust the dosage of medication, so it is usually done every 2 weeks. After the dosage of medication has been adjusted and serum thyroid stimulating hormone and thyroid hormone have been maintained as normal, the baby will be rechecked every three months. After thyroid function is restored to normal, it should be rechecked every 6 months after 1-2 years. If the child experiences significant discomfort, or if the symptoms worsen significantly, the thyroid function needs to be rechecked in a timely manner and there is no time rule.