Galactorrhea is the secretion of a milky discharge from the breast that occurs spontaneously or is easily expressed, unrelated to pregnancy or breastfeeding. This phenomenon involves milk production outside of the typical postpartum period. While more common in women, galactorrhea can also affect men and infants, indicating an underlying issue with the hormonal regulation of milk production. It is considered a symptom of an underlying condition rather than a disease itself.
Visual Characteristics and Presentation
The discharge characteristic of galactorrhea is typically milky or white, resembling human milk, often confirmed by the presence of fat droplets within the fluid. The appearance can sometimes vary, ranging from a clear or slightly watery fluid to a faint yellow or even green discharge. It is important to distinguish this milky fluid from other types of nipple discharge, such as bloody, clear, or purulent fluid, as these suggest different and potentially more concerning pathologies.
A defining feature of true galactorrhea is that the discharge is usually bilateral and often involves multiple milk ducts. The volume of the discharge varies significantly; for some, it may be a constant, spontaneous leak requiring breast pads, while for others, it is only noticeable when the breast is gently squeezed or stimulated. Discharge that is unilateral or comes from only a single duct is generally not characteristic of galactorrhea and may prompt a different diagnostic path.
The discharge often requires physical stimulation to appear, such as manipulation during examination, but it can also be spontaneous. Excessive handling of the nipple or breast area, including during sexual activity, can sometimes induce this discharge in individuals sensitive to the milk-producing hormone. This type of discharge, which is non-bothersome and occurs only with breast stimulation, may not require treatment if other laboratory values are normal.
Primary Causes of Galactorrhea
The underlying mechanism for most cases of galactorrhea involves an elevated level of the hormone prolactin, a condition known as hyperprolactinemia. Prolactin is primarily produced by the pituitary gland, a small organ at the base of the brain. Any factor that interferes with the regulation of this hormone, which is responsible for stimulating milk production, can lead to inappropriate milk secretion.
A common pathological cause is a prolactinoma, a benign tumor of the pituitary gland that secretes excessive prolactin. The size of this tumor often correlates with the level of prolactin in the blood. Other issues with the pituitary or hypothalamus, such as non-prolactin-secreting tumors, can also cause galactorrhea by compressing the pituitary stalk. This compression disrupts the flow of dopamine, the substance that normally inhibits prolactin release.
Pharmacological agents are a frequent cause, as many medications can inadvertently increase prolactin levels. These include certain classes of antipsychotics, antidepressants, antihypertensive drugs, and some opioids. These medications often work by blocking dopamine receptors, removing the natural brake on prolactin secretion from the pituitary gland. Stopping or switching the offending drug will usually resolve the galactorrhea.
Systemic diseases can also contribute to galactorrhea by affecting hormonal balance or the body’s ability to clear prolactin. Hypothyroidism, an underactive thyroid gland, can lead to increased prolactin secretion because the thyrotropin-releasing hormone (TRH) that stimulates the thyroid also stimulates prolactin release. Chronic kidney disease can cause hyperprolactinemia because the kidneys become less efficient at metabolizing and clearing prolactin from the bloodstream, causing it to accumulate.
Physical causes may also trigger galactorrhea through nerve stimulation that mimics the suckling reflex. Excessive manipulation of the breast, such as frequent self-examinations or intense nipple friction from tight clothing, can activate this reflex. Chest wall trauma, surgery, or nerve irritation from conditions like shingles (herpes zoster) can also send signals to the hypothalamus, leading to a temporary rise in prolactin and subsequent discharge.
Medical Evaluation and Treatment Overview
Evaluation for galactorrhea begins with a thorough medical history and physical examination to identify potential underlying causes. The assessment includes examining the discharge, noting its color, consistency, and whether it comes from one or multiple ducts. Unilateral or bloody discharge is more suggestive of other conditions requiring immediate attention. The evaluation also includes a detailed review of all medications, including over-the-counter drugs and herbal supplements, which may be contributing to the issue.
Initial laboratory testing typically includes a pregnancy test for women of reproductive age, and a serum prolactin level to determine if hyperprolactinemia is present. Thyroid-stimulating hormone (TSH) and renal function tests are also commonly performed to screen for hypothyroidism and chronic kidney disease. If the prolactin level is significantly elevated or if the patient reports associated symptoms like persistent headaches or changes in vision, brain imaging (MRI) may be necessary to check for a pituitary adenoma.
The treatment approach focuses on managing the underlying cause, as the discharge itself is a symptom. If a medication is identified as the culprit, a healthcare professional may adjust the dosage or suggest an alternative drug. For cases related to hypothyroidism or chronic kidney disease, treating the primary systemic condition will generally resolve the galactorrhea. When a prolactinoma is the cause, medications known as dopamine agonists, such as cabergoline, are often prescribed to lower prolactin levels and potentially shrink the tumor. If no specific cause is found and the discharge is minimal, observation and reassurance may be the recommended path.