Prolactinoma

Question 1

Define prolactinoma

Answer 1

Benign lactotroph adenomas expressing and secreting prolactin -> secondary hypogonadism
Microadenoma <10mm, small intrasellar tumours
Macroadenoma >10mm, large with suprasellar or parasellar invasion

Question 2

What are the causes/risk factors of prolactinomas?

Answer 2

• Female
• Genetic predisposition

Other causes of hyperprolactinaemia
• Primary hypothyroidism (↑TRH -> ↑ prolactin release)
• Dopamine antagonists e.g. metoclopramide
• PCOS
• Acromegaly (tumour secretes GH and prolactin)

Question 3

What are the symptoms of prolactinomas?

Answer 3

• Oligo/amenorrhea
• Infertility
• Galactorrhoea
• Reduced libido
• Erectile dysfunction
• Bilateral hemianopia
• Headaches
• Osteoporosis (low sex steroids)

Question 4

What are the signs of prolactinomas?

Answer 4

none

Question 5

What investigations are carried out for prolactinomas?

Answer 5

• Serum Prolactin: Elevated. Serum prolactin levels usually correlate with the size of the Prolactinoma.
• Sex hormones – GNRH inhibited
• TSH and ACTH – other anterior hormones too
• Pituitary MRI: A gadolinium-enhanced MRI of the pituitary is able to detect small micro-adenomas, and define the extension of invasive macro-adenomas. Supra-sellar growth is seen.
• Computerised Perimetry: To investigate visual field loss. Can use Humphrey or Goldmann Perimetry instead.

Question 6

What is the management for prolactinomas?

Answer 6

Conservative:
• Observation –in asymptomatic women (incidentalomas) with microadenomas and no desire of pregnancy.

Medical:
• Dopamine Receptor (D2) Agonists: Cabergoline and Bromocriptine.
- These reduce the secretion of prolactin from the prolactinoma since hypothalamic DA has a physiological inhibitory effect on lactotroph prolactin secretion. This treats the hyperprolactinaemia.
- They also reduce the tumour size.

Surgical:
• Trans-sphenoidal Hypophysectomy.
- This is done in patients who do not tolerate their medications or are unresponsive to it.

Radiological:
• Sellar Radiotherapy
- It is reserved for situations where medical and surgical treatments have failed, and for the rare cases of malignant prolactinomas.

Question 7

What are the complications of prolactinomas?

Answer 7

• bitemporal hemianopia
• hypopituitarism
• pituitary apoplexy
• CSF leak
• Bromocriptine and Cabergoline: Nausea and vomiting, Postural hypotension, Dyskinesias, Depression, Pathological Gambling.