Prolactinoma

Question 1

Definition of prolactinoma

Answer 1

Benign lactotroph adenomas that overexpress and secrete prolactin

Question 2

Aetiology and pathophysiology of prolactinoma

Answer 2

• Majority of them occur sporadically
• Is the commonest functional pituitary adenoma

• Hypersecretion of prolactin causes secondary hypogonadism:
◦ The prolactin would bind to the prolactin receptors on the kisspeptin neurones in the hypothalamus
◦ This would inhibit kisspeptin release
◦ This would reduce the release of gonadotropin releasing hormones from the neurones
◦ This would reduce the release of FSH and LH from the gonadotrophs
◦ This would reduce the relapse of testosterone and oestrogen, resulting in symptoms
Other causes of hyperprolactinaemia:
• Pregnancy/breast feeding
• Venepuncture/stress
• Nipple/chest wall stimulation
• PCOS
• Antipsychotics
• SSRI’s

Question 3

History and Examination of prolactinoma

Answer 3

• FEMALE:
‣ Amenorrhoea or Oligomenorrhoea: menstrual disturbance one of the most common symptoms
‣ Infertility
‣ Galactorrhoea: milk production outside of post-partum period
‣ Loss of libido
‣ Increased weight, vaginal dryness etc
‣ Symptoms present earlier in women

• MEN:
◦ Erectile dysfunction
◦ Decreased libido
◦ Reduced facial hair
◦ Osteoporosis: due to low testosterone/estradiol level
◦ Usually later presentation

• Headache
• Visual disturbances: Bitemporal hemianopia

Question 4

Risk factors for prolactinoma

Answer 4

• Female
• 20-50 years old

Question 5

Investigations for prolactinoma

Answer 5

• Serum prolactin: Can be collected at any time of the day. Be wary of macroprolactin (stick together to give false positive result) and stress of venepuncture (increases prolactin falsely). Serum prolactin correlates with the size of the tumour
• Pituitary MRI: once TRUE elevation of prolactin has been confirmed, then do pituitary MRI to visualise tumour

Question 6

Treatment for prolactinoma

Answer 6

Asymptomatic, microprolactinomas:
1) Observation: Does not require treatment

Symptomatic:
1) Dopamine agonist: Medical treatment with CABERGOLINE (dopamine agonist) is first line. Start at low doses and increase to reduce prolactin levels and shrink tumour

2) Trans-sphenoidal surgery

Question 7

Complications and prognosis of prolactinoma

Answer 7

• Visual field impairment: bitemporal hemianopia
• Anterior pituitary failure and/or diabetes insipidus: Trans-sphenoidal surgery can be complicated with anterior pituitary failure and/or diabetes insipidus needing permanent hormonal replacement
• Pituitary apoplexy

Good prognosis when treated accordingly with dopamine agonist