Pituitary adenoma !
A pituitary adenoma is a benign tumour of the pituitary gland; it can upset hormone levels or press on the nerves of vision.
Updated 2026-10-29
Structures involved
Tap one to see what it is and open it in 3D.
- Pituitary gland
- Sella turcica
- Optic chiasm
- Sphenoid sinus
- Cavernous sinus
- Hypothalamus
- Internal carotid artery
- Oculomotor nerve (III)
- Abducens nerve (VI)
In biochemistry
In histology
In the clinical exam
In physiology
- The hypothalamic–pituitary system: overview
- The thyroid axis: reading TSH and free T4
- Measuring hormones: stimulation and suppression tests
- Growth hormone and IGF-1
- Prolactin and its control by dopamine
- Functions of the hypothalamus
- The visual pathway, pupillary reflexes and eye movements
Why it happens
What it is
A benign tumour of the anterior pituitary gland. It can cause symptoms by secreting excess hormone, by reducing other hormones, or by pressing on nearby structures such as the optic chiasm.
Who gets it
Common: small incidental adenomas are frequently found on brain imaging. Clinically relevant tumours are most often diagnosed in adults; prolactinomas are the most frequent functioning type.
Causes
- Mostly sporadic, from monoclonal growth of a pituitary cell type
- Inherited syndromes in a minority (e.g. multiple endocrine neoplasia type 1, familial isolated pituitary adenoma)
Risk factors
- Adulthood
- Family history of pituitary tumours or MEN1
Pathophysiology
A pituitary cell line proliferates within the sella turcica. Functioning tumours secrete prolactin, growth hormone, ACTH or, rarely, TSH. Larger tumours compress normal pituitary tissue (hypopituitarism), push the stalk (raising prolactin by blocking dopamine), grow up to the optic chiasm or sideways into the cavernous sinus.
Classification
- Microadenoma (under 10 mm) and macroadenoma (10 mm or more)
- Functioning: prolactinoma, somatotroph (acromegaly), corticotroph (Cushing disease), thyrotroph
- Non-functioning (clinically silent)
Symptoms and signs
- Bitemporal hemianopia and other visual field loss
- Headache
- Prolactinoma: amenorrhoea, galactorrhoea, infertility, low libido, erectile dysfunction
- Acromegaly: enlarged hands, feet and jaw, coarse facial features, sweating
- Cushing disease: central obesity, purple striae, hypertension, diabetes
- Hypopituitarism: fatigue, cold intolerance, sexual dysfunction
Diagnosis
- Clinical
- Symptoms of hormone excess or deficiency and visual field testing; many tumours are found incidentally on imaging.
- Tests
- Pituitary hormone panel: prolactin, IGF-1, morning cortisol and ACTH, TSH and free T4, gonadotrophins and sex hormones; dynamic tests for excess (e.g. glucose suppression for GH, dexamethasone suppression for cortisol). Formal visual field testing.
- Imaging
- Pituitary MRI with gadolinium defines size and extension to the optic chiasm, cavernous sinus and sphenoid sinus.
Differential diagnosis
- Craniopharyngioma
- Rathke cleft cyst
- Meningioma of the sellar region
- Lymphocytic hypophysitis
- Physiological pituitary enlargement (pregnancy, primary hypothyroidism)
- Drug-induced hyperprolactinaemia
Goal of treatment
Normalise hormone excess, replace deficient hormones, relieve compression of the optic pathway and other structures, and prevent regrowth.
Treatment
- Medical
- Prolactinomas: dopamine agonists are first line and usually shrink the tumour.
- Surgical
- Transsphenoidal surgery for most other symptomatic adenomas (acromegaly, Cushing disease, non-functioning tumours with visual loss).
- Medical
- Somatostatin analogues or GH receptor antagonists for persistent acromegaly; drugs that lower cortisol for persistent Cushing disease; hormone replacement for deficiencies.
- Procedure
- Radiotherapy or radiosurgery for residual or recurrent tumours.
- Follow-up
- Small non-functioning incidental adenomas: periodic MRI, hormone tests and visual fields.
Drugs for this condition
Complications
- Permanent visual loss
- Hypopituitarism, including adrenal insufficiency
- Pituitary apoplexy
- Diabetes insipidus or hyponatraemia after surgery
- Cardiovascular disease, diabetes and osteoporosis from long-standing hormone excess
Prognosis
Benign, and most patients do well with appropriate treatment. Large invasive tumours and some functioning tumours can persist or recur and need long-term follow-up.
Test yourself
Think of the answer, then tap the question to see it.
Which visual field defect is classic for a pituitary macroadenoma?
Bitemporal hemianopia, from compression of the crossing fibres at the optic chiasm.
What is the first-line treatment for most prolactinomas?
Dopamine agonists, which lower prolactin and usually shrink the tumour.
Why can a non-functioning macroadenoma raise prolactin?
Compression of the pituitary stalk blocks dopamine from the hypothalamus, which normally inhibits prolactin release.
What is pituitary apoplexy?
Sudden haemorrhage or infarction of a pituitary tumour, causing severe headache, visual loss, eye movement palsies and adrenal crisis.
Which surgical approach is used for most pituitary adenomas?
Transsphenoidal surgery, through the sphenoid sinus.
Related conditions
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Pituitary Adenoma (StatPearls (NCBI Bookshelf), 2025).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.
