There are several reasons why prolactin continues to increase after surgery for prolactinoma: 1. Tumor residual: Tumor cells infiltrate into the surrounding important structures (e.g. important blood vessels, nerves, etc.), and if this part of the tumor continues to be removed, it will cause serious consequences, so this part has to be left behind. 2. Disorder of endocrine regulation center. Some scholars suggest that the occurrence of pituitary tumor is caused by the disorder of the central hypothalamic endocrine regulation system. Even if the tumor is completely eradicated, the disorder cannot be removed and there is continuous hyperprolactinemia. 3. PRL secretion inhibitory hormone disorder: Before and after surgery, PRL secretion inhibitory hormone is disordered due to tumor compression or surgical harassment, which cannot control the secretion of PRL cells, and PRL level is increased due to PRL hypersecretion. Treatment: 1. If the tumor is obviously left behind during the surgery, the surgeon should or is obliged to inform the patient’s family after the surgery that the patient needs to continue the appropriate treatment after the surgery. 2. If the prolactin continues to increase significantly after surgery, it is usually due to the residual tumor and should be observed for 1-2 months. If the prolactin is still mildly elevated, the PRL level should be monitored dynamically, and rechecked once every 1-2 months. If the level does not return to normal after 6 months, a repeat MRI is needed. If no obvious tumor residue is found, medication may be added for younger patients. Older patients can continue to be observed. 3. Do not take radiation therapy for young patients, because once they receive it, their chances of having children are obviously reduced.