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# Prolactinoma (hyperprolactinaemia)

A benign pituitary tumour that makes too much prolactin. It stops periods, causes milk discharge and infertility, and usually shrinks with tablets.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Pituitary gland](https://durgical.com/en/anatomy/pituitary-gland/)
- [Sella turcica](https://durgical.com/en/anatomy/sella-turcica/)
- [Optic chiasm](https://durgical.com/en/anatomy/optic-chiasm/)
- [Hypothalamus](https://durgical.com/en/anatomy/hypothalamus/)
- [Cavernous sinus](https://durgical.com/en/anatomy/cavernous-sinus/)
- [Sphenoid sinus](https://durgical.com/en/anatomy/sinus-of-sphenoid-bone/)
- [Optic nerve](https://durgical.com/en/anatomy/optic-nerve/)

## In embryology

- [Pituitary gland: Rathke pouch and the neurohypophysis](https://durgical.com/en/embryology/pituitary-gland-rathke-pouch-and-the-neurohypophysis/)

## Why it happens

- [Prolactin and its control by dopamine](https://durgical.com/en/physiology/prolactin-and-its-control-by-dopamine/)
- [The hypothalamic–pituitary system: overview](https://durgical.com/en/physiology/the-hypothalamic-pituitary-system-overview/)
- [The menstrual cycle: ovary and endometrium](https://durgical.com/en/physiology/the-menstrual-cycle-ovary-and-endometrium/)
- [Pituitary: adenohypophysis and neurohypophysis](https://durgical.com/en/histology/pituitary-adenohypophysis-and-neurohypophysis/)

## What it is

A benign tumour of the lactotroph cells of the anterior pituitary that secretes excess prolactin. It is the most common hormone-secreting pituitary adenoma and the classic cause of pathological hyperprolactinaemia.

## Who gets it

The most frequent functioning pituitary tumour worldwide and in Latin America. Microprolactinomas predominate in women of reproductive age; men tend to present later with larger tumours because early symptoms are less obvious.

## Causes

- Monoclonal growth of prolactin-secreting lactotroph cells, usually sporadic
- Occasionally part of an inherited syndrome, most often multiple endocrine neoplasia type 1
- Other causes of high prolactin must be excluded: pregnancy, drugs that block dopamine, hypothyroidism, [kidney](https://durgical.com/en/anatomy/kidney/) failure and stalk compression

## Risk factors

- Female sex, ages 20 to 50 for microadenomas
- Family history of MEN 1
- Oestrogen exposure may promote growth of an existing tumour (e.g. in pregnancy)

## Pathophysiology

Prolactin is normally held in check by dopamine from the [hypothalamus](https://durgical.com/en/anatomy/hypothalamus/). Excess prolactin suppresses hypothalamic GnRH pulses, so LH, FSH and sex steroids fall, causing anovulation, amenorrhoea, low testosterone and bone loss. A large tumour can also compress the [optic chiasm](https://durgical.com/en/anatomy/optic-chiasm/) above the sella or the normal pituitary, causing visual loss and hypopituitarism.

## Classification

- Microprolactinoma: under 10 mm
- Macroprolactinoma: 10 mm or more, may invade the cavernous sinus
- Giant prolactinoma: 40 mm or more

## Symptoms and signs

- Women: oligomenorrhoea or amenorrhoea, galactorrhoea and infertility
- Men: low libido, erectile dysfunction, infertility and sometimes gynaecomastia
- Headache with larger tumours
- Visual field loss, classically bitemporal hemianopia, with macroadenomas
- Reduced bone density from long-standing low sex hormones

## Red flags

- Sudden severe headache with vision loss or eye-movement palsy (pituitary apoplexy)
- Rapidly worsening visual field loss
- Clear nasal fluid leak (CSF rhinorrhoea) after tumour shrinkage with medical treatment
- Signs of adrenal insufficiency (hypotension, vomiting, confusion) from loss of other pituitary hormones

## Diagnosis

**Clinical**
Menstrual and fertility history, galactorrhoea, sexual function, visual field testing by confrontation, and a careful drug history.

**Tests**
Serum prolactin (marked elevation supports a prolactinoma); pregnancy test, TSH and free T4, and creatinine to exclude other causes. In a large tumour with only mild elevation, a diluted sample excludes the hook effect. Other pituitary axes (morning cortisol, LH, FSH, sex steroids, IGF-1) are assessed in macroadenomas. Formal visual field perimetry.

**Imaging**
Pituitary MRI with gadolinium is the imaging study of choice; it sizes the tumour and shows extension to the chiasm or [cavernous sinus](https://durgical.com/en/anatomy/cavernous-sinus/).

## Differential diagnosis

- Pregnancy and breastfeeding
- Drug-induced hyperprolactinaemia (antipsychotics, metoclopramide and other dopamine antagonists)
- Primary hypothyroidism
- Stalk effect from a non-functioning macroadenoma or craniopharyngioma
- Chronic kidney disease and macroprolactinaemia

## Goal of treatment

Normalise prolactin, restore gonadal function and fertility, shrink the tumour and protect vision, while preserving the rest of pituitary function.

## Treatment

**Medical**
Dopamine agonists (cabergoline, bromocriptine) are first-line even for macroadenomas with visual loss; they lower prolactin and shrink most tumours. Valvular heart disease is monitored when high cumulative doses are used.

**Surgical**
Transsphenoidal surgery for intolerance or resistance to dopamine agonists, apoplexy, or vision that does not improve.

**Procedure**
Radiotherapy is reserved for aggressive tumours not controlled by medicine and surgery.

**Follow-up**
Serial prolactin, repeat MRI and visual fields; closer follow-up in pregnancy because a macroadenoma can enlarge.

## Drugs for this condition

- [Cabergoline](https://durgical.com/en/pharmacology/cabergoline/)
- [Bromocriptine](https://durgical.com/en/pharmacology/bromocriptine/)

## Complications

- Infertility and amenorrhoea
- Osteoporosis from long-standing hypogonadism
- Visual loss from chiasmal compression
- Hypopituitarism and pituitary apoplexy
- CSF leak after rapid tumour shrinkage

## Prognosis

Most microprolactinomas are controlled with medication and some never grow. Many patients can eventually taper treatment, but prolactin may rise again, so long-term follow-up is needed.

## Test yourself

Think of the answer, then tap the question to see it.

## What is the first-line treatment of a prolactinoma, even with visual field loss?

A dopamine agonist such as cabergoline or bromocriptine; surgery is reserved for intolerance, resistance or apoplexy.

## Why does hyperprolactinaemia cause amenorrhoea and low testosterone?

Prolactin suppresses hypothalamic GnRH pulsatility, so LH and FSH fall and the gonads make less sex steroid.

## Which visual field defect is classic for a pituitary macroadenoma?

Bitemporal hemianopia, from compression of the optic chiasm.

## Which common conditions must be excluded before blaming a pituitary tumour for high prolactin?

Pregnancy, dopamine-blocking drugs (e.g. antipsychotics), primary hypothyroidism and kidney failure.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/conditions/prolactinoma/)

## Related conditions

- [Pituitary adenoma](https://durgical.com/en/conditions/pituitary-adenoma/)
- [Hypopituitarism (incl. Sheehan syndrome and pituitary apoplexy)](https://durgical.com/en/conditions/hypopituitarism/)
- [Male hypogonadism](https://durgical.com/en/conditions/male-hypogonadism/)
- [Multiple endocrine neoplasia (MEN 1, 2A, 2B)](https://durgical.com/en/conditions/multiple-endocrine-neoplasia/)
- [Hypothyroidism](https://durgical.com/en/conditions/hypothyroidism/)
- [Osteoporosis](https://durgical.com/en/conditions/osteoporosis/)
- [Polycystic ovary syndrome](https://durgical.com/en/conditions/polycystic-ovary-syndrome/)
- [Functional hypothalamic amenorrhoea](https://durgical.com/en/conditions/functional-hypothalamic-amenorrhoea/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Prolactinoma](https://medlineplus.gov/ency/article/000336.htm) (MedlinePlus Medical Encyclopedia (U.S. National Library of Medicine), 2025).

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Source: https://durgical.com/en/conditions/prolactinoma/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/prolactinoma/