Prolactinoma Management

Excerpt

Prolactinomas comprise nearly 40% of all pituitary tumors. Patients with prolactinomas usually come to medical attention as a result of symptoms caused by elevated prolactin levels, such as hypogonadism, menstrual irregularities, infertility or galactorrhea, or due to mass effects. Sometimes these patients can present as an emergency, either due to a visual field defect or loss of vision, or due to acute severe headache caused by pituitary apoplexy associated with hypopituitarism. Most patients with hyperprolactinemia do not have prolactinomas. A number of physiological conditions as well as several medications can also cause prolactin elevations; in these instances, prolactin levels are usually < 150 ng/mL (3000 mIU/L). Hyperprolactinemia can also result from reduced dopamine reaching the lactotrophs due to stalk compression. Furthermore, when evaluating patients with only modestly elevated prolactin levels and large macroadenomas, one should be aware of the “hook effect”, caused by saturation of antibodies of a two-site immunoassay by very high prolactin levels. A dopamine agonist is the treatment of choice in the vast majority of cases. Dopamine agonists can normalize prolactin levels, restore the function of the gonadal axis, stop galactorrhea, and significantly decrease tumor size in most of the patients, with cabergoline generally being more efficacious and better tolerated than bromocriptine. Indeed, cabergoline is first-line therapy even in patients with visual field defects, as long as visual acuity is not threatened by rapid progression or recent tumor hemorrhage. Cerebrospinal fluid leakage is a rare complication of dopamine agonists if they cause rapid tumor shrinkage and there is disruption of the sellar floor by the tumor. Transsphenoidal surgery is an alternative treatment in cases of dopamine agonist resistance or intolerance. Radiation therapy is reserved for those rare patients with macroadenomas not responding to either medical or surgical treatment. Symptomatic growth during pregnancy may occur in about 20-25% of macroprolactinomas, and therefore visual field testing is indicated each trimester in such patients. MRI scans (without gadolinium) are done in those patients who develop visual field defects or severe headaches when a therapeutic intervention is contemplated. Prolactinoma is the most common pituitary tumor subtype in children and adolescents and macroprolactinomas are more frequent in this age group compared to adults. In addition to typical symptoms of hyperprolactinemia, pediatric patients may present with delayed or arrested puberty, growth failure, and weight gain. Many aspects of the care for children and adolescents with prolactinomas are similar to that in adults; however, key differences exist, particularly in presentation and etiology. For that reason, children and adolescents with pituitary adenomas, including prolactinomas, should be treated by a pituitary specific multidisciplinary team. For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text, WWW.ENDOTEXT.ORG.