Galactorrhea is the spontaneous bilateral discharge of milky ﬂuid from the nipples. (Many women, especially those who have given birth, can express small amounts of milky ﬂuid from one or both nipples, and this is not considered abnormal.) Galactorrhea is uncommon but reports vary from 1% to 30%, depending on the population studied. Although not inherently dangerous, galactorrhea can be the harbinger of signiﬁcant underlying physiologic disruptions and, as such, deserves careful evaluation.
Because galactorrhea represents a symptom, multiple causes can result in the same clinical presentation. Pituitary adenoma or hypothyroidism can result in elevated prolactin levels, which can stimulate the breast parenchyma and result in milk secretion. Galactorrhea can also result as a side effect from pharmacologic agents. Most often this occurs with those drugs that affect dopamine or serotonin production or metabolism. (Some foods when consumed in excess can mimic this same process, notably licorice.) Some autoimmune diseases (sarcoid, lupus) or Cushing disease may result in the patient’s symptoms. Chronic chest wall irritation such as from herpes zoster, breast stimulation, or breast irritation may result in the activation of neural pathways normally associated with physiologic milk production. Chronic stimulation of these neural pathways can result in galactorrhea. Physiologic changes during pregnancy or after childbirth and/or nursing may lead to persistent milk secretion. Most pathologic processes that lead to galactorrhea result in an elevation of serum prolactin levels. This can be helpful in evaluating the source and threat posed by these symptoms.
Galactorrhea is often accompanied by other presenting complaints or conditions: one-third of patients with an elevated prolactin level experience amenorrhea or infertility. Prolonged hypogonadal amenorrhea resulting from hyperprolactinemia is associated with an increased risk of osteoporosis, vaginal and genital atrophic changes, dyspareunia, and libidinal dysfunction.
The evaluation of the patient with galactorrhea will, in part, be dictated by any associated symptoms suggestive of an underlying process. In the absence of other symptoms, measurement of serum prolactin levels begins the evaluation process. (Pregnancy should always be considered if menses are absent.) Prolactin should be measured in the fasting, resting state because eating and stress can increase levels. An elevated serum prolactin level suggest the need for radiologic evaluation of the pituitary. The preferred approach is computed tomography or magnetic resonance imaging of the sella turcica. Unfortunately, there is a poor correlation between serum prolactin levels and the size of a pituitary lesion. Testing of visual ﬁelds may be indicated if there is a pituitary macroadenoma (10 mm).
When prolactin levels are low and imaging of the sella turcica is normal, observation alone may be sufﬁcient. If observation is chosen, periodic reevaluation is required to check for the emergence of slow-growing tumors. Treatment with bromocriptine is recommended for patients who desire pregnancy, have distressing degrees of galactorrhea, or have macroadenomas. Unfortunately, medical therapy may be associated with nausea, orthostatic hypotension, drowsiness, or syncope, hypertension, or seizures, and bromocriptine therapy may interact with phenothiazines or butyrophenones.
Medical therapy is generally effective for patients with hyperprolactinemia. Prolactin levels should be measured every 6 to 12 months and visual ﬁelds reassessed yearly. The pituitary should be reevaluated every 2 to 5 years, based on the initial diagnosis. The patient’s symptoms may recur when medical therapy is discontinued.
Rapidly growing tumors, tumors that are large at the time of discovery, or those that do not respond to bromocriptine therapy may require surgical or radiation therapy. Surgery can often be accomplished via the transsphenoidal approach. Surgical therapy may result in complete loss of pituitary function requiring careful replacement and monitoring of other endocrine systems, including the thyroid and adrenal.