Description

• Milky nipple discharge not associated with lactation, defined as >1 year after pregnancy or cessation of breastfeeding.
• Does not include serous, purulent, or bloody nipple discharge
• System(s) affected: endocrine/metabolic, nervous, reproductive

Pediatric Considerations
Can occur in infants secondary to maternal estrogen exposure

Pregnancy Considerations
Milk production often begins during the second trimester; milk leakage that occurs during pregnancy is not pathophysiologic galactorrhea.

Epidemiology

• Predominant age: 15 to 50 years (reproductive age), most commonly ages 20 to 35 years
• Third most common breast complaint in women

Incidence
Marked variability reported

Prevalence
Approximately 20–25% of women experience galactorrhea in their lifetime.

Etiology and Pathophysiology

• Oxytocin stimulates the anterior pituitary to secrete prolactin, which induces lactation.
• Prolactin secretion is inhibited by dopamine produced in the hypothalamus.
• Galactorrhea results either from prolactin overproduction or loss of inhibitory regulation by dopamine.
• Physiologic galactorrhea can be due to pregnancy, nipple stimulation, nipple piercing, exercise, or sexual activity.
• Hyperprolactinemia can be due to overproduction by malignancy or mass effect, most commonly prolactinoma.
• Hyperprolactinemia secondary to systemic diseases:
  • Hypothyroidism
  • Chronic renal failure (reduced clearance of prolactin leading to elevated serum levels)
  • Cirrhosis
  • Adrenal insufficiency
• Medications/substances:
  • Cardiovascular (α-methyldopa, reserpine, verapamil, spironolactone)
  • GI (domperidone, metoclopramide)
  • Herbal (anise [licorice], barley, blessed thistle, fenugreek seed, fennel, goat’s rue)
  • Illicit (cocaine, marijuana)
  • Antimicrobials (isoniazid, protease inhibitors)
  • Opioids
  • Psych/neuro (neuroleptics, antipsychotics, stimulants, SSRIs, tricyclic antidepressants, MAOIs)
  • Reproductive (estrogens, copper IUD)
  • DMARDs (azathioprine)

General Prevention

• Avoid frequent nipple stimulation.
• Avoid medications that can suppress dopamine.

Commonly Associated Conditions

• Commonly associated with hypothyroidism, chronic kidney disease, hypogonadism, and pituitary adenoma
• Rarely associated with adrenal insufficiency, chest wall conditions/trauma, post-breast reduction surgery, acromegaly