Prolactin is one of the hormones secreted by the pituitary gland. Prolactin secretion is high in women during late pregnancy and lactation, which promotes mammary gland development and secretion of milk. The highest serum levels of prolactin in non-pregnant women generally do not exceed 20 μg/L. Elevated prolactin should be considered physiological, pharmacological and disease factors, as follows: 1. Physiological increase: seen in exercise, pregnancy, postpartum, breast sucking, nighttime sleep stress and menstrual secretion; 2. Pharmacological effects: including oral contraceptives, cimetidine, chlorpromazine, other phenothiazines, certain antihistamines, α-methyldopa, synthetic prolactin, and other drugs. The increase in prolactin levels in the blood is caused by oral contraceptives, cimetidine, chlorpromazine, other phenothiazines, certain antihistamines, alpha-methyldopa, synthetic thyroid hormone-releasing hormone, general anesthetics, arginine and insulin-induced hypoglycemia, etc.; 3, pathological increase: seen in hypothalamic diseases, such as pituitary prolactinomas, hypothalamic tumors, pituitary growth hormone tumors, ectopic growth of tumors, endocrine organ lesions, such as Cushing’s syndrome, acromegaly, adrenal function hypothyroidism, primary hypothyroidism combined with increased TRH, as well as gonadal hormone disorders, liver and kidney diseases.