Prolactinoma

Question 1

What is a prolactinoma?

Answer 1

Pituitary adenoma (benign lactotroph adenomas) that overproduces prolactin.

Question 2

Describe the aetiology of prolactinoma

Answer 2

UNKNOWN

99% sporadic

Question 3

Describe the epidemiology of prolactinomas

Answer 3

Relatively common
Most common type of pituitary adenoma
Higher incidence in premenopausal women

Question 4

List 5 signs and symptoms of prolactinoma in women

Answer 4

Amenorrhoea/oligomenorrhoea  
Galactorrhoea  
Infertility  
Hirsuitism  
Reduced libido

Question 5

List 3 signs and symptoms of prolatinoma in men

Answer 5

Symptoms are subtle + develop slowly
Reduced libido
Reduced beard growth
Erectile dysfunction

Question 6

Describe the classification of prolactinoma based on size

Answer 6

Microadenomas: < 1 cm
Macroadenomas: > 1 cm
Giant Pituitary Adenomas: > 4 cm
Malignant Prolactinoma (RARE)

Question 7

List 4 signs and symptoms caused by the size of prolactinoma

Answer 7

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

Question 8

What is the relationship between microprolactinomas and macroprolactinomas?

Answer 8

microprolactinomas rarely expand to become macroprolactinomas

Question 9

List 4 risk factors for prolactinomas

Answer 9

Female 20-50yrs
Genetic predisposition; MEN-1 mutation
Male 30-60yrs
Oestrogen therapy

Question 10

List investigations for prolactinoma

Answer 10

Serum prolactin level (extremely high > 5000 mU/L) suggests true prolactinoma
TFTs: hypothyroidism -> high TRH –> stimulates prolactin release
MRI: esp if visual defect is noted
Assessment of pituitary function

Question 11

What additional investigation should be carried out in women with suspected prolactinoma?

Answer 11

Pregnancy test

Question 12

What are the goals of treatment of prolactinoma?

Answer 12

Treat cause
Relieve symptoms
Prevent complications
Restore fertility

Question 13

What drugs are used in treatment of prolactinoma? Why? Give 2 examples

Answer 13

Dopamine Agonists (e.g. cabergoline + bromocriptine) - DOPAMINE IS LIKE THE BRAKE ON PROLACTIN PRODUCTION

Question 14

Describe the use of dopamine agonists in patients with prolactinoma

Answer 14

Effective in most patients
Cabergoline is used 1st line due to better efficacy + reducing tumour size + better tolerability
Usually need to be continued on a long-term basis

Question 15

What management approaches are used if medical management is unsuccessful in prolactinomas?

Answer 15

Surgery: transphenoidal hypophysectomy
Radiotherapy: rarely used; only if meds + surgery have failed

Question 16

List 3 complications of hypogonadism in prolactinoma

Answer 16

Osteoporosis
Reduced fertility
Erectile dysfunction

Question 17

List 4 complications of tumour size in prolactinoma

Answer 17

Visual loss
Headache
Pituitary apoplexy
CSF rhinorrhoea

Question 18

What is the prognosis for prolactinomas?

Answer 18

Microprolactinomas spontaneously resolve in ~ 1/3 cases
Dopamine agonist withdrawal is usually attempted after 2-3 years if prolactin levels have normalised + tumour volume is reduced
High rates of recurrence

Question 19

Describe the physiology of prolactin secretion

Answer 19

Stimulated by: TRH

Inhibited by: Dopamine

Question 20

Describe the physiological effects of high prolactin

Answer 20

Negative feedback to hypothalamus, increases dopamine release which then decreases prolactin levels.
Decrease secretion of GnRH + thus FSH + LH