High serum thyrotropin (TSH) means that the pituitary gland synthesizes and secretes more of the hormone, resulting in high blood levels of the hormone, which is commonly seen in primary hypothyroidism, iodine-deficiency endemic goiter, and pituitary tumors. TSH is a hormone synthesized and secreted by the pituitary gland and regulated by the hypothalamus, which promotes the secretion of thyroid hormones by the thyroid gland. High TSH can be seen in primary hypothyroidism, subclinical hypothyroidism, Hashimoto’s thyroiditis with hypothyroidism, exogenous thyroid hormone-producing tumors (e.g., lung cancer, breast cancer, etc.), iodine-deficiency endemic goiter, and pituitary tumors. When TSH is found to be high, one should consult a doctor in time to improve the examination of T3, T4, thyroid autoantibodies, neck ultrasound, etc., so as to make a clear diagnosis and take appropriate treatment.