Endocrine · Year 2 · from Endocrine

Case 2: Prolactinoma with Amenorrhea-Galactorrhea Syndrome

Patient Demographics

  • Age: 28 years
  • Sex: Female
  • Occupation: Marketing consultant

Chief Complaint

"I haven't had my period in 8 months and I'm leaking milk from my breasts."

History of Present Illness

A 28-year-old woman presents with secondary amenorrhea for 8 months and bilateral breast discharge for 4 months. She is not pregnant (multiple negative pregnancy tests) and is not taking any medications that could cause these symptoms. She reports decreased libido and has noticed occasional headaches. She and her husband have been trying to conceive for the past year without success. She denies visual changes.

Physical Examination

  • Vital Signs: BP 116/72 mmHg, HR 68 bpm
  • General: Well-appearing woman in no distress
  • Breast: Bilateral milky discharge expressible from multiple ducts
  • Pelvic: Normal external genitalia, vaginal mucosa appears slightly atrophic
  • Visual Fields: Full to confrontation
  • Neurologic: Normal

Workup

  • Laboratory Studies:
  • Prolactin: 186 ng/mL (markedly elevated, normal <25)
  • β-hCG: Negative
  • TSH: 2.1 mIU/L (normal)
  • FSH: 3.2 mIU/mL (low)
  • LH: 2.8 mIU/mL (low)
  • Estradiol: 22 pg/mL (low)
  • MRI Pituitary with Contrast: 12 mm pituitary adenoma (macroadenoma) confined to sella

Diagnosis

Prolactinoma (macroprolactinoma) causing:

  1. Galactorrhea
  2. Secondary amenorrhea (hypogonadotropic hypogonadism)
  3. Infertility

Treatment

  1. First-line: Dopamine agonist therapy
  • Cabergoline 0.25-0.5 mg twice weekly (preferred - more effective, fewer side effects)
  • Alternative: Bromocriptine 2.5 mg daily
  1. Goals: Normalize prolactin, restore menstrual function, reduce tumor size
  2. Follow-up: Repeat prolactin in 1 month, MRI in 3-6 months
  3. Pregnancy considerations: Can attempt conception once prolactin normalizes; discontinue cabergoline when pregnant
  4. Surgery reserved for: Medication intolerance or resistance

Clinical Pearl

Prolactinomas are the most common functioning pituitary adenomas (40% of all pituitary tumors). Unlike other pituitary adenomas, the first-line treatment is medical therapy with dopamine agonists, not surgery. Cabergoline is preferred over bromocriptine due to better efficacy and tolerability. The degree of prolactin elevation generally correlates with tumor size - a "stalk effect" from non-functioning adenomas typically causes prolactin levels <100 ng/mL, while true prolactinomas cause elevations proportional to tumor mass. A 12mm tumor with prolactin of only 40-50 ng/mL should raise suspicion for a non-functioning adenoma with stalk effect.

Clinical Image

Coronal T1-weighted MRI with gadolinium showing a pituitary macroadenoma consistent with prolactinoma.

Image Source: Radiopaedia - "Prolactinoma" License: CC BY-NC-SA 3.0 URL: https://radiopaedia.org/cases/prolactinoma-3

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