[Don't miss prolactinoma! On the importance of measuring prolactin and how it is done].

Prolactinoma is the most common functional pituitary tumor. Since appropriate treatment is often pharmacological rather than surgical, all patients with a tumor within or close to the sella turcica should be evaluated for prolactinoma before being sent for neurosurgery. Preanalytical factors affecting serum prolactin concentration should be taken into account when planning blood sampling. Diagnostic laboratories should aim for the use of common international calibrators and a common unitage for expressing concentrations. Assays should be carried out in such a way that the risk of falsely high or low values is minimized. Any patient with high values due to an immunometric method should be evaluated for the possible presence of endogenous antibodies against prolactin ("macroprolactinemia").