PRL is synthesized and secreted by eosinophilic PRL cells in the pituitary gland. Remind patients to check the precautions: 1, PRL secretion is unstable, emotions, exercise, sexual intercourse, hunger and eating can affect its secretion state, and with the menstrual cycle has a small fluctuation, with sleep-related rhythm; short-term secretion of PRL increases after sleep, and higher in the afternoon than in the morning. Therefore, according to this rhythmic secretion characteristic, blood should be drawn at 9~10 am on an empty stomach. It is better to be quiet for 1 hour. 2, PRL significantly elevated, a test can be determined; PRL mildly elevated, a second examination should be carried out, can not be easily diagnosed with hyperprolactinemia (HPRL) and abuse of bromocriptine treatment. 3, PRL ≥ 25 ng / ml or higher than the normal value of the unit test for HPRL. PRL50 ng / ml, about 20% have prolactinoma. PRL100 ng / ml, about 50% have prolactinoma, can be selective pituitary CT or magnetic resonance. PRL200 ng / ml, there is often a micro-adenoma, you have to do the CT or magnetic resonance of the pituitary. 4, PRL lowering: Silhan syndrome, use of anti-PRL drugs such as bromocriptine, levodopa, VitB6, etc..