Pituitary hypothyroidism, also known as secondary hypothyroidism, refers to hypothyroidism caused by a decrease in TSH secretion from the pituitary gland, which leads to a decrease in the secretion of T3 and T4 from the thyroid gland. When lesions occur in the pituitary gland, such as pituitary tumors, postpartum hemorrhage, etc., it will lead to a decrease in TSH secretion by the pituitary gland, and a decrease in TSH will lead to a decrease in thyroid hormone secretion, thus causing secondary hypothyroidism. Therefore, the main manifestations of pituitary hypothyroidism in laboratory tests are lower TSH and lower T3 and T4. The following points should be noted in the treatment of pituitary hypothyroidism: 1) Active treatment of primary diseases, such as pituitary tumors, etc. 2) Pituitary hypothyroidism also requires lifelong replacement therapy with levothyroxine sodium, which requires regular rechecking of thyroid function and adjustment of drug doses during the treatment process. 3) When judging the dose of replacement therapy drugs, only T4 and not TSH should be used as the standard for adjusting drug doses.