Pituitary tumour

Question 1

What is a pituitary tumour?

Answer 1

An abnormal growth in the pituitary gland.
Pituitary adenomas that do not cause a characteristic hormone hypersecretion syndrome are known as “Non- functional adenomas” and those that do are known as “Functional adenomas” (e.g. acromegaly, cushing’s, prolactinoma)

Question 2

What causes pituitary tumours?

Answer 2

Most occur sporadically, some cases have genetic association (Multiple Endocrine Neoplasia Type 1)
- MEN 1 (3 P’s) ⇒ parathyroid, pituitary, pancreas. Typically presents as hypercalcaemia.

Question 3

Summarise the epidemiology of non-functioning pituitary tumours

Answer 3

● Most common type of macroadenoma (> 1 cm)
● Most common type of pituitary tumour in patients > 60 yrs

Question 4

What are the presenting symptoms/ signs of a pituitary tumour?

Answer 4

*Symptoms develop very SLOWLY because there are no hormonal derangements
*Pressure on surrounding structures:

1. Non Functioning → panhypopituitarism + bitemporal hemianopia + headache
   a. Bitemporal Hemianopia → due to pressure on optic chiasm
   - Upper quadrant defect > Lower quadrant defect = inferior chiasmal compression, typically pituitary tumour
   - Lower quadrant defect > Upper quadrant defect = superior chiasma compression, typically craniopharyngioma
   b. Panhypopituitarism → tumour may compress other parts of the pituitary gland
   - Non-Functioning tumours typically present with generalised hypopituitarism
   - Low ACTH ⇒ tiredness, postural hypotension
   - Low FSH/LH ⇒ amenorrhoea, infertility, loss of libido
   - Low TSH ⇒ feeling cold, constipation
   c. Headache
2. Functioning →
   - Prolactinoma=
   a. Women → amenorrhoea, infertility, galactorrhoea, osteoporosis
   b. Men → impotence, loss of libido, galactorrhoea
   - Acromegaly ⇒ increase in shoe and hand size, large tongue, excessive sweating, OSA.
3. Other Macroadenoma Signs → headache, visual disturbances, symptoms of hypopituitarism

Question 5

How are pituitary tumours classified?

Answer 5

1. Size → Microadenoma ≤10mm (1cm) or Macroadenoma >10mm (1cm)
2. Hormonal Status → Functional (secretes hormone) or Non-Functional (doesn’t produce hormone in excess)
   - Functional ⇒ prolactinoma (prolactin secreting), acromegaly (GH secreting), cushing’s disease (ACTH secreting)

Question 6

What investigations are used to diagnose/ monitor pituitary tumours?

Answer 6

1. Brain MRI
2. Pituitary Blood Profile → GH, prolactin, ACTH, FH, LSH, TFTs
   - Determine whether mass is functioning or non-functioning
3. Acromegaly → serum IGF-1 (initial), OGTT (diagnostic), serum GH (pulsatile hence less reliable)
   - OGTT with serial GH measurements → would lead to a paradoxical rise (no suppression) in GH following glucose load
4. Prolactinoma → serum prolactin
5. Visual Field Testing

Question 7

How are pituitary tumours managed?

Answer 7

1. Microadenoma or Asymptomatic Macroadenoma → Observation
2. Macroadenoma (>10mm) → Trans-Sphenoidal Surgery
3. Prolactinoma → 1st Line = Bromocriptine or Cabergoline (Dopamine Agonists- dopamine bind to D2 receptors on lactotrophs to release prolactin). 2nd Line (if medical treatment fails) = Surgery.
4. Acromegaly → 1st Line = Trans-Sphenoidal Surgery. 2nd Line = somatostatin analogue (octreotide)-“off switch” for GH BUT can switch off goof hormones (e.g. CCK in gut); not a long term fix

Question 8

What is meant by “carcinoid syndrome”?

Answer 8

• Due to NET (neuroendocrine tumour) secreting serotonin
• Leads to flushing, diarrhoea, SOB
• Ix ⇒ urinary 5-HIAA
• Tx ⇒ octreotide (somatostatin analogue)