Acromegaly & Prolactinoma

Question 1

What conditions arise from functioning pituitary tumours?

Which hormone is involved in each?

Answer 1

Acromegaly + gigantism: Growth hormone

Prolactinoma: prolactin

Cushing’s: cortisol

Question 2

What’s the difference between acromegaly and gigantism?

Answer 2

Both caused by a tumour secreting excess GH

Gigantism = tumour occurs before fusion of epiphyseal plates

Acromegaly = tumour occurs after they’ve stopped growing

Question 3

Clinical features of gigantism?

Answer 3

They grow unusually tall, but growth is linear

Delayed puberty

Question 4

Clinical features of acromegaly?

Answer 4

Often insidious onset

Enlargement of hands and feet
Prognathism: enlargement of jaw
Interdental spacing

Severe headaches
Excess sweating
Arthralgias
Hypogonadal symptoms

Question 5

What are come comorbidities of acromegaly?

Answer 5

Hypertension and heart disease
Sleep apnoea
Insulin-resistant diabetes
Cerebrovascular events
Arthritis

Question 6

What causes mortality in acromegaly?

Answer 6

Cardiac involvement

Question 7

Investigation of acromegaly?

Answer 7

Cannot use GH as a test because it varies so much during the day

Rely on IGF-1 levels and OGTT

IGF-1 would be raised in acromegaly

OGTT: raised blood glucose usually inhibits GH release. So raise patients blood glucose with sugary drink, and see if GH levels drop. If they don’t drop below a certain level (1) they have acromegaly

Head MRI to look for pituitary adenoma

Question 8

What does IGF-1 stand for?

Answer 8

Insulin like growth factor 1

Question 9

Pathogenesis of acromegaly?

Answer 9

Increased GH production directly causes excess growth

Also causes increased secretion IGF-1 from the liver which causes excess growth

Question 10

Why is the glucose tolerance test used to diagnose acromegaly?

Answer 10

Raised blood glucose usually inhibits GH release. So raise patients blood glucose with sugary drink, and see if GH levels drop. If they don’t drop below a certain level (1) they have acromegaly

Question 11

Treatment of acromegaly?

Answer 11

Surgical: decompression tumour (mainstay)

Medical:

• somatostatin analogues: octreotide - first line
• dopamine agonist: bromocriptine, cabergoline

Radiotherapy: to shrink tumour

Question 12

What is prolactinoma?

Answer 12

Tumour of lactotroph cells in pituitary

Causes excess production of prolactin

Question 13

Who gets prolactinoma?

Answer 13

Women more than men

Question 14

Why is the physiology of prolactinoma release different to other hormones?

Answer 14

It is under inhibition of release by dopamine

Question 15

Clinical presentation of prolactinoma?

Answer 15

Local effect of tumour:

• visual problems
• raised ICP

Menstrual irregularity
Infertility
Galactorrhoea
Low libido
Low testosterone in men

Question 16

Management of prolactinoma?

Answer 16

Dopamine agonist: cabergoline is highly effective

Question 17

When faced with a patient who has a pituitary tumour and has visual problems you should operate immediately.

True or false?

Answer 17

FALSE!

Always check prolactin levels first, because if it is a prolactinoma it is completely curable with cabergoline

Surgery is not necessary

Question 18

List the drugs used to treat acromegaly. Explain why they help? Give an example of each.

Answer 18

1st line: somatostain analogue: octreotide!
Somatostatin is also known as GH inhibiting hormone, so giving analogues will help inhibit GH

2nd line: dopamine agonist: bromocriptine, cabergoline
Prevents release of GH from pituitary

3rd: pegvisomant (genetically modified human GH)

Question 19

The more dopamine, the ___ prolactin released?

Answer 19

The more dopamine, the less prolactin released