During treatment with growth hormone deficiency dwarfism, about 19-30% of patients will develop hypothyroidism, mainly in the form of reduced serum T4 or free T4 levels, often without changes in serum T3 and TSH levels. However, most patients do not have the typical clinical manifestations of hypothyroidism and are mainly subclinical hypothyroid. In order to avoid negative effects on growth hormone therapy, thyroid hormone supplementation is needed in a timely manner. Therefore, we need to monitor the thyroid function of these children during the course of treatment. Possible reasons why these children are prone to subclinical hypothyroidism include the presence of a defect in the hypothalamic-pituitary-thyroid axis, which may be manifested by the application of exogenous GH, the increased peripheral conversion of T4 to T3 by growth hormone therapy, and the suppression of TSH secretion by increased secretion of growth inhibitory hormone in these children.