Whether a woman’s breasts produce milk or not depends mainly on the level of prolactin in her body. The level of prolactin in the body of a normal teenage girl is very low and can only maintain the development of the mammary glands, but cannot stimulate the breasts to secrete milk. Therefore, lactation in adolescent girls is an abnormal phenomenon due to an abnormal increase in the level of prolactin in the body. The main reasons for this are: 1) a tumor in the pituitary gland of the hypothalamus; 2) although no tumor has occurred, the cells of the pituitary gland are stimulated by the prolactin-promoting factor secreted by the hypothalamus, resulting in excessive secretion of prolactin, called hyperprolactinemia, which is often accompanied by amenorrhea. The diagnosis can be further confirmed by cranial CT or transmagnetic resonance imaging and measurement of serum prolactin levels. If there is a tumor it can be treated with gamma knife and cured without craniotomy: if it is not a tumor but only hyperprolactinemia, bromocriptine can be taken, but only under medical supervision. Third, other factors such as destructive or inflammatory lesions (tuberculosis, meningitis, etc.), primary hypothyroidism, hypoadrenalism, and drug factors (taking dormantine, reserpine, opioids, etc.) can cause increased prolactin and cause lactation.