Prolactinoma

Question 1

Define

Answer 1

Benign, prolactin-producing tumours of the pituitary gland

Prolactin stimulates lactation

Raised levels lead to hypogonadism, infertility and osteoporosis, by inhibiting secretion of GnRH
(Hence ↓LH/FSH and ↓testosterone or oestrogen)

Question 2

Causes

Answer 2

Microprolactinomas: A tumour <10mm on MRI (~25% of us have asymptomatic microprolactinomas) Treat with bromocriptine or cabergoline

Macroprolactinomas: A tumour >10mm diameter on MRI
As they are near the optic chiasm, there may be ↓acuity, diplopia, ophthalmoplegia, visual-field loss, and optic atrophy
Treat medically initially; later consider trans-sphenoidal surgery

Giant Pituitary Adenomas: > 4 cm

Malignant Prolactinoma (RARE)

Cause if UNKNOWN

Some may occur as a consequence of MEN 1 syndrome

Risk Factors

• Risk of tumour enlargement in pregnancy

Question 3

Epidemiology

Answer 3

It presents earlier in women (menstrual disturbance) but later in men (e.g. with erectile dysfunction and or mass effects)

Question 4

Symptoms

Answer 4

NOTE: microprolactinomas rarely expand to become macroprolactinomas

Women

• Amenorrhoea/oligomenorrhoea
• Galactorrhoea
• Infertility
• Hirsuitism
• Reduced libido

Men

• Symptoms are subtle and develop slowly
• Reduced libido
• Reduced beard growth
• Erectile dysfunction

Symptoms caused by tumour size

• Headache
• Visual disturbance (bitemporal hemianopia)
• Cranial nerve palsies
• Signs and symptoms of hypopituitarism

May present late with osteoporosis or local pressure effects from the tumour

Question 5

Investigation

Answer 5

Exclude pregnancy

TFTs - hypothyroidism –> high TRH –> stimulates prolactin release

Serum prolactin level (extremely high levels (> 5000 mU/L) suggests true prolactinoma)

MRI

Assessment of pituitary function

Question 6

Management

Answer 6

Goals

• Treat cause
• Relieve symptoms
• Prevent complications
• Restore fertility

Dopamine Agonists (e.g. cabergoline and bromocriptine)

• Effective in most patients
• Usually need to be continued on a long-term basis

If dopamine agonists are ineffective:

• Surgery
• Radiotherapy

Question 7

Complications

Answer 7

Complications of hypogonadism

• Osteoporosis
• Reduced fertility
• Erectile dysfunction

Complications of tumour size

• Visual loss
• Headache
• Pituitary apoplexy
• CSF rhinorrhoea

Question 8

Prognosis

Answer 8

Microprolactinomas will spontaneously resolve in about 1/3 cases

Dopamine agonist withdrawal is usually attempted after about 2-3 years if prolactin levels have normalised and tumour volume is reduced

High rates of recurrence