Galactorrhoea and high prolactin: the AU general practice workup

Galactorrhoea — milky nipple discharge occurring more than six months after childbirth or in someone who has never been pregnant — is one of those presentations that initially generates concern but resolves straightforwardly in the majority of cases once a logical workup is completed. It accounts for roughly 0.1% of general practice encounters in Australia, predominantly in women of reproductive age, though it also occurs in men and occasionally in children with certain hormonal disturbances.

The foundational principle in general practice is a clean binary decision at the first assessment: is this true galactorrhoea (bilateral, milky, multi-duct — an endocrine question), or is it pathological nipple discharge (unilateral, blood-stained, single duct — a breast surgery question)? Conflating the two pathways leads to missed diagnoses in both directions.

A. Core clinical — the AU general-practice framework

The bilateral versus unilateral decision

Cancer Australia’s clinical guidance on breast symptom investigation is clear: unilateral, blood-stained, serosanguinous, or clear serous discharge from a single duct requires triple-test pathway assessment (clinical examination + breast imaging + biopsy), not an endocrine workup. Conditions in that category include intraductal papilloma, ductal carcinoma in situ (DCIS), and invasive breast carcinoma.

True galactorrhoea has the opposite characteristics: bilateral, milky or opalescent (occasionally clear-yellow or faint green), expressible from multiple ducts, and confirmed fat-globule positive on microscopy when uncertain. Spontaneous discharge staining the bra is a common history. Men with prolactinomas typically present later because galactorrhoea is rarer in males — their presentation is usually sexual dysfunction, infertility, or headache.

History

The drug history is the single highest-yield part of the history, and medication review should occur before any blood test. Antipsychotics — particularly risperidone, paliperidone, and amisulpride — are the leading medication cause, with prolactin levels sometimes exceeding 3000–4000 mIU/L on these agents. Antiemetics (metoclopramide, domperidone, prochlorperazine), SSRIs, opioids, methyldopa, verapamil, and oestrogen-containing contraceptives can all cause varying degrees of prolactin elevation through dopamine receptor blockade or other mechanisms.

Menstrual history is equally important: oligo/amenorrhoea or irregular cycles indicate that the hyperprolactinaemia is causing secondary hypogonadism — a clinically significant finding that increases bone loss risk and warrants treatment even if galactorrhoea alone is mildly distressing.

Neurological symptoms — new persistent headaches, peripheral visual field narrowing (“bumping into things on the side”), diplopia — must be actively screened. These suggest a macroadenoma with proximity to the optic chiasm or cavernous sinus.

Examination

Breast examination confirms the laterality, duct number, and character of discharge. Gentle manipulation of both nipples can demonstrate whether discharge is expressible, and its colour and consistency should be documented. Visual fields by confrontation are performed at the initial consultation for any patient with neurological symptoms or when prolactin is markedly elevated. Signs of hypothyroidism (dry skin, bradycardia, slow reflexes, goitre), acromegaly (coarse facies, large hands, prognathism), or Cushing syndrome (striae, central obesity) should be screened for systematically.

Investigations

First-line workup per RACGP AJGP guidance and eTG Endocrinology:

• βhCG — exclude pregnancy before interpreting any other result
• Serum prolactin — taken fasting, morning, rested, without breast examination or vigorous exercise in the preceding hour; repeat if abnormal to confirm
• TSH ± free T4 — primary hypothyroidism is a reversible cause of elevated prolactin via TRH-mediated stimulation of lactotrophs
• Urea, electrolytes, eGFR — chronic kidney disease causes modest prolactin elevation
• LFTs and FBC — baseline
• Medication review — the most important non-laboratory step

Interpreting prolactin levels:

The Endocrine Society 2011 guideline provides a clinically useful framework. Prolactin 500–1000 mIU/L suggests drug effect, stress artefact, macroprolactin, or mild stalk effect. Levels 1000–2000 mIU/L fit drug effect, microadenoma, or idiopathic. Levels above 2000 mIU/L are usually microprolactinoma; above 5000 mIU/L, macroprolactinoma until proven otherwise.

Macroprolactin (biologically inactive prolactin bound to immunoglobulin) should be requested when prolactin is elevated but there are no symptoms — the PEG precipitation test demonstrates whether the elevated level is biologically active.

MRI pituitary with gadolinium (MBS item 63007, specialist referral required for rebate) is indicated for confirmed persistent unexplained hyperprolactinaemia after drug and thyroid causes have been excluded.

B. Treatment — addressing the underlying cause

Drug-induced hyperprolactinaemia

This is the most common reversible cause. Review with the prescribing clinician — particularly the psychiatrist for antipsychotic medications — is essential. Unilateral discontinuation of antipsychotic medication carries serious risk of psychiatric decompensation and must never be done without specialist input. NPS MedicineWise and the AMH both note that aripiprazole has partial dopamine agonist activity and substantially lower prolactin-elevating effect than other antipsychotics, making it a candidate for switch under psychiatric supervision where clinically appropriate.

Hypothyroidism

Confirmed primary hypothyroidism causing galactorrhoea responds to levothyroxine titrated to target TSH. Prolactin normalises as thyroid status corrects, typically over weeks to months. No additional prolactin-lowering treatment is required in this scenario.

Prolactinoma

The AMH and Endocrine Society 2011 concur that cabergoline (PBS Authority Required — Streamlined) is the preferred first-line agent for symptomatic prolactinaemia or prolactinoma. Starting at 0.25 mg twice weekly and titrating to 0.5–1 mg twice weekly, it normalises prolactin in 80–90% of microprolactinomas and 70–80% of macroprolactinomas, with tumour shrinkage of 50–80% over 6–12 months. The landmark Webster NEJM 1994 trial established its superiority over bromocriptine in both efficacy and tolerability.

Bromocriptine (PBS Authority Required) remains the preferred agent when conception is being actively planned, due to its longer track record of safety in pregnancy.

All patients on cabergoline must be counselled explicitly about impulse control disorders — compulsive gambling, hypersexuality, and compulsive shopping — a rare but documented class effect across dopamine agonists. This is a medico-legal requirement per NPS MedicineWise guidance.

Macroprolactinaemia

No treatment is needed. The elevated prolactin reflects biologically inactive prolactin-immunoglobulin complexes with no clinical consequences. Reassurance and annual surveillance are appropriate.

Asymptomatic idiopathic mild hyperprolactinaemia

The Endocrine Society 2011 does not recommend treatment for mild, asymptomatic idiopathic elevation. Annual monitoring with repeat prolactin is appropriate.

C. Monitoring and follow-up framework

Prolactin is rechecked 4–6 weeks after starting or adjusting a dopamine agonist, then 3-monthly until stable, then 6–12 monthly for established prolactinoma. MRI at 6–12 months after starting cabergoline for macroprolactinoma documents tumour response; less frequent imaging once shrinkage is confirmed. Formal visual field testing (Humphrey perimetry, specialist, MBS item 11221) is performed at baseline and post-treatment for any adenoma with chiasmal proximity.

Bone density (DEXA, MBS item 12306) is indicated at baseline and 2-yearly when prolonged hypogonadism is present — oestrogen deficiency from hyperprolactinaemia-suppressed GnRH causes bone loss that may not fully reverse with prolactin normalisation.

Withdrawal of dopamine agonist may be trialled after at least two years of sustained normal prolactin with imaging showing tumour resolution or absence of visible adenoma. Approximately 25–30% of patients achieve durable remission off treatment per the Sala JCEM 2016 review; annual surveillance for five years after withdrawal is recommended.

D. Australian operations

MBS items: Standard GP consultations (23, 36, 44). Prolactin and the initial bundle (TSH, βhCG, UEC, FBC, LFT) are standard pathology items. MRI pituitary with contrast is item 63007 (specialist referral needed for Medicare rebate in most circumstances). Visual field testing is item 11221 (specialist). DEXA is item 12306. Endocrinology initial consultation is rebated under items 132/133. Breast surgery referral for pathological discharge is covered under item 105/106.

PBS: Cabergoline is on PBS Authority Required (Streamlined) for hyperprolactinaemia and prolactinoma. Bromocriptine is on PBS Authority Required. Quinagolide is not PBS-listed in Australia.

GPCCMP: A confirmed prolactinoma qualifies as a chronic condition for the GP Chronic Condition Management Plan (items 965/967), enabling structured allied health referrals including psychology for fertility or sexual distress, exercise physiology for bone health, and dietitian for calcium and vitamin D optimisation.

E. Special populations

Pregnancy and fertility seeking: For women with microprolactinoma planning pregnancy, the Endocrine Society guideline recommends ceasing cabergoline at confirmed conception — microprolactinomas rarely grow to a clinically significant degree during pregnancy. Macroprolactinomas carry a higher risk of growth; endocrinology should be involved in pre-conception planning. Bromocriptine is preferred over cabergoline when conception is being actively attempted due to its longer established safety record in pregnancy.

Men: Macroprolactinomas present more commonly in men because galactorrhoea is a less obvious symptom — presentation is typically through sexual dysfunction (reduced libido, erectile dysfunction) or mass effects. The workup and treatment pathway is identical.

Older women post-menopause: Galactorrhoea is rarer in postmenopause due to lower oestrogen. Its presence warrants a thorough drug review and imaging even with mild prolactin elevations, as the threshold for symptoms differs.

Aboriginal and Torres Strait Islander patients: ATSI Health Assessment (item 715) provides an opportunity to screen for and document endocrine conditions. Cultural safety and clear communication about the nature of pituitary investigations are important.

When to escalate

Refer urgently to emergency if: pituitary apoplexy (sudden severe headache, visual loss, collapse), acute bitemporal hemianopia, or new cranial nerve palsy — these suggest haemorrhage or infarction into a pituitary adenoma and can cause acute hypopituitarism.

Refer soon to endocrinology for: confirmed pathological hyperprolactinaemia of any cause, any visible pituitary adenoma, intolerance or non-response to first-line treatment, active fertility planning with prolactinoma, and macroprolactinoma without acute mass effect.

Refer to breast surgery for: unilateral, bloody, serous, or single-duct discharge — do not treat this as galactorrhoea.

What this article is and is not

This article draws on RACGP AJGP guidance, Therapeutic Guidelines (eTG), the AMH, the Endocrine Society 2011 guideline, and the Pituitary Society 2023 consensus. It is general health information for educational purposes and does not constitute personal medical advice or create a doctor–patient relationship.

For consumer-friendly Australian resources: HealthDirect, Better Health Channel, and the Australian Pituitary Foundation.

For acute emergency symptoms — sudden severe headache, visual loss, collapse — call 000.

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Sources cited

1. RACGP — AJGP Galactorrhoea and hyperprolactinaemia review
2. Therapeutic Guidelines (eTG) — Endocrinology: Hyperprolactinaemia
3. Australian Medicines Handbook — cabergoline and bromocriptine
4. NPS MedicineWise — impulse control disorders with dopamine agonists
5. Endocrine Society — Hyperprolactinaemia Guideline 2011 (Melmed)
6. Pituitary Society — Prolactinoma management (Petersenn 2023)
7. Cancer Australia — Investigation of a new breast symptom
8. Webster J et al. — Cabergoline versus bromocriptine (NEJM 1994)
9. HealthDirect — galactorrhoea
10. Australian Pituitary Foundation
11. Better Health Channel