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Endocrinology & Metabolic

Pituitary Adenoma

A pituitary adenoma causes illness through hormone excess, local mass effect, or loss of normal pituitary function; urgent recognition of visual compromise, adrenal insufficiency and pituitary apoplexy matters more than the scan label alone.

In a nutshell

Pituitary adenomas cause hormone excess, mass effect or hypopituitarism. Think of a prolactinoma, acromegaly or Cushing disease when there is a hormone syndrome; think of chiasmal compression when there is bitemporal field loss. MRI, pituitary hormone assessment and visual assessment guide pituitary MDT management.

Classic presentation

A patient with headache and difficulty seeing to the sides has a sellar mass extending towards the optic chiasm, with endocrine testing showing either a specific hormone excess or pituitary deficits.

Key points

  • A pituitary lesion can secrete hormones, compress the chiasm or normal gland, or do more than one of these.
  • Bitemporal visual field loss localises to optic-chiasm compression and requires urgent specialist assessment.
  • A modest prolactin rise may be stalk effect; do not label every sellar mass a prolactinoma.
  • The prolactinoma is usually treated medically first; other subtypes need subtype-specific MDT treatment and often surgery.
  • Replace corticosteroid before thyroid hormone when secondary adrenal insufficiency is possible.
  • Sudden severe headache with visual or neurological features is pituitary apoplexy until assessed.

First-line investigation

Dedicated pituitary MRI plus endocrine assessment and formal visual assessment when the lesion is near the optic apparatus.

Management

Identify emergencies

  • Escalate sudden severe headache, visual loss, ophthalmoplegia, altered consciousness, hypotension or suspected adrenal crisis as possible pituitary apoplexy.6,5

Characterise the lesion

  • Arrange dedicated pituitary MRI, endocrine assessment and visual assessment when the lesion is near the optic apparatus or symptoms suggest compression.2,1

Treat the subtype

  • Use dopamine agonist treatment for prolactinoma where appropriate; manage other functioning tumours and compressive lesions through the pituitary MDT, often including transsphenoidal surgery.3,4

Replace deficient hormones

  • Identify and replace pituitary hormone deficits safely, prioritising corticosteroid replacement before thyroid hormone when adrenal insufficiency is possible.5,1

Protect vision

  • Arrange urgent ophthalmic and neurosurgical input for progressive visual loss or chiasmal compression; select surgery or medical shrinkage according to tumour type and anatomy.4,2

Surveil recurrence and complications

  • Continue specialist-directed MRI, endocrine and visual follow-up, with surveillance for recurrence, hypopituitarism and complications of hormone excess.2,3

Exam traps

  • A macroadenoma is defined by size, not by whether it secretes a hormone.
  • A prolactin rise from stalk compression is usually modest compared with a true prolactinoma, but assay interpretation belongs with endocrinology.
  • Diabetes insipidus is atypical for a simple anterior pituitary adenoma.
  • Do not delay emergency corticosteroid treatment while waiting for a complete endocrine work-up when apoplexy with adrenal compromise is suspected.

Illustrations

Pituitary macroadenoma on MRICoronal post-contrast MRI showing a pituitary macroadenoma expanding the sella and extending into the right cavernous sinus beside the internal carotid artery.Cerevisae, Wikimedia Commons · CC-BY-SA-4.0

Key sources

  1. The Pituitary Foundation: tests for pituitary conditions (UK pituitary service information explaining hormone testing, dynamic tests, MRI and visual assessment; accessed 4 August 2026.)
  2. Pituitary Society consensus guideline for pituitary incidentaloma (Nature Reviews Endocrinology consensus on endocrine assessment, dedicated imaging, visual assessment, specialist referral and individualized surveillance or surgery for sellar and parasellar incidental findings; published 24 June 2025 and accessed 4 August 2026.)Updated 24 Jun 2025
  3. Pituitary Society international consensus statement on the diagnosis and management of prolactinomas (Current specialist consensus covering biochemical evaluation, imaging, dopamine agonists, surgery, radiotherapy, withdrawal and pregnancy/fertility decisions; published 5 September 2023 and accessed 4 August 2026.)Updated 5 Sept 2023
  4. NICE HTG14: Endoscopic transsphenoidal pituitary adenoma resection (NICE interventional procedures guidance supporting use with consent, audit and governance and stating that the procedure should be performed by experienced clinicians in an appropriate multidisciplinary centre; accessed 4 August 2026.)
  5. British National Formulary (BNF) (Current UK prescribing information for pituitary hormones, dopamine agonists and corticosteroid replacement; product-specific details must be checked at the point of care; accessed 4 August 2026.)
  6. 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.)
  7. Pituitary Society update to acromegaly management guidelines (Specialist consensus on diagnosis, surgery, medical treatment, radiotherapy and comorbidity surveillance in acromegaly; 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.