Diagnostic evaluation of hyperprolactinemia.

A serum prolactin (PRL) level is obtained in response to a specific clinical presentation, including symptoms of hyperprolactinemia (such as amenorrhea and galactorrhea); serum PRL measurement may also be performed as part of an infertility evaluation. An initial level above the normal range should be followed by a repeat level from a blood sample drawn in the morning with the patient in a fasting state. The medical history and a few laboratory tests can eliminate the most common physiologic and pharmacologic causes of hyperprolactinemia, including pregnancy, primary hypothyroidism and treatment with drugs (such as neuroleptics) that reduce dopaminergic effects on the pituitary. In the absence of such causes, radiologic imaging of the sella turcica is necessary to establish whether a PRL-secreting pituitary adenoma or other lesion is present. The vast majority of patients are treated medically, with dopamine agonist drugs. Surgery is reserved for the patient with the uncommon tumor that does not respond to medical therapy or has a large cystic component or for the occasional patient who cannot tolerate dopamine agonists or who experiences pituitary apoplexy.