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Endocrinology & Metabolic

Hyperprolactinaemia

Hyperprolactinaemia is a raised prolactin concentration caused by physiology, medicines, systemic disease, stalk interruption or a prolactinoma; confirm the result and find the cause before treating the number.

In a nutshell

Hyperprolactinaemia causes galactorrhoea, menstrual disturbance, infertility, low libido and hypogonadism by suppressing the reproductive axis. Exclude pregnancy, medicines and secondary disease, repeat the result and consider macroprolactin or the hook effect. A prolactinoma is usually treated first with a dopamine agonist, commonly cabergoline.

Classic presentation

A patient with amenorrhoea, galactorrhoea or infertility has persistent raised prolactin after pregnancy, medication and thyroid causes are considered; MRI may show a micro- or macroprolactinoma.

Key points

  • Dopamine tonically inhibits prolactin; dopamine antagonists and stalk compression raise it.
  • Repeat and contextualise the prolactin before diagnosing a prolactinoma.
  • Check pregnancy, the medication list, thyroid function and renal/systemic disease.
  • A large mass with a modest prolactin may be stalk effect or hook effect; discuss dilution with the laboratory.
  • Cabergoline is usually first-line for a prolactinoma, with specialist planning for visual symptoms, fertility and pregnancy.

First-line investigation

Repeat serum prolactin with pregnancy, medication, thyroid and systemic-cause assessment; arrange pituitary MRI when the elevation remains unexplained or a prolactinoma is suspected.

Management

Escalate visual or apoplexy features

  • Arrange urgent pituitary assessment for visual field loss, ophthalmoplegia or sudden severe headache with neurological or haemodynamic features.4,2

Confirm the cause

  • Repeat prolactin and check pregnancy, medicines, thyroid function and systemic causes before labelling the result a prolactinoma.2,1,5

Treat a prolactinoma medically

  • Use endocrinology-directed dopamine-agonist therapy, usually cabergoline, with product-specific prescribing checked in the BNF.2,8

Protect reproductive and bone health

  • Address hypogonadism, fertility, pregnancy planning and bone health through endocrine and fertility specialists.5,2,1

Use surgery selectively

  • Consider transsphenoidal surgery or other specialist treatment for medical intolerance, resistance, selected compressive disease or an acute complication.2,6

Monitor response and tumour

  • Follow prolactin, symptoms, visual status, gonadal function and tumour size, and review whether treatment can be reduced or withdrawn only through specialist assessment.2,8

Exam traps

  • Galactorrhoea is not required for hyperprolactinaemia.
  • Do not stop an antipsychotic abruptly just to lower prolactin.
  • A modest prolactin rise does not prove a prolactinoma.
  • A very large prolactinoma can produce a falsely low result through the hook effect.
  • Pregnancy and visual symptoms in a patient with a macroprolactinoma require urgent specialist advice.

Illustrations

Prolactinoma on histologyH&E histology of a prolactin-producing pituitary adenoma, a common pathological cause of persistent hyperprolactinaemia.Jensflorian, Wikimedia Commons · CC-BY-SA-3.0

Key sources

  1. The Pituitary Foundation: prolactinoma (Current UK information on causes, symptoms, testing, dopamine-agonist treatment, fertility and pregnancy considerations; accessed 4 August 2026.)
  2. Pituitary Society international consensus statement on the diagnosis and management of prolactinomas (Specialist consensus covering biochemical evaluation, macroprolactin and assay issues, imaging, dopamine agonists, surgery, radiotherapy, withdrawal and pregnancy/fertility decisions; published 5 September 2023 and accessed 4 August 2026.)Updated 5 Sept 2023
  3. The Pituitary Foundation: tests for pituitary conditions (UK pituitary service information on prolactin testing, MRI, visual assessment and endocrine investigations; accessed 4 August 2026.)
  4. Society for Endocrinology: pituitary apoplexy clinical guidance (UK Society for Endocrinology clinical guidance resource for recognition and emergency management of pituitary apoplexy; accessed 4 August 2026.)
  5. NICE NG257: Fertility problems: assessment and treatment (Current NICE recommendation to offer cabergoline for ovulatory disorders due to hyperprolactinaemia, with specialist fertility management; accessed 4 August 2026.)
  6. NICE HTG14: Endoscopic transsphenoidal pituitary adenoma resection (NICE guidance supporting use with consent, audit and governance and requiring experienced clinicians in an appropriate multidisciplinary centre; accessed 4 August 2026.)
  7. Pituitary Society consensus guideline for pituitary incidentaloma (Consensus on imaging, visual assessment and specialist management of sellar lesions that may produce stalk effect or compress the optic apparatus; published 24 June 2025 and accessed 4 August 2026.)Updated 24 Jun 2025
  8. British National Formulary (BNF) (Current UK prescribing information for cabergoline, bromocriptine and pituitary hormone replacement; product-specific details must be checked at the point of care; accessed 4 August 2026.)

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.