HPA axis disorders AB

Question 1

Acromegaly - investigations?

Answer 1

Elevated IGF1

Oral glucose load - positive test if failure to suppress GH

MRI pituitary

Question 2

Acromegaly - treatment?

Answer 2

Surgery (trans-sphenoidal if small, hypophysectomy if large) +/- RTx

Consider dopamine agonist or somatostatin analogue

Survival benefit for normalising post-surgery elevated IGF

Question 3

GH deficiency - investigation?

Answer 3

IGF-1

Insulin tolerance test - failure to rise appropriately

Question 4

Ectopic ACTH - manifestations?

Answer 4

Hyperpigmentation
Severe myopathy
Hypokalaemia
Very high cortisol and ACTH

Question 5

Pseudocushing’s - causes?

Answer 5

EtOH

Depression

Question 6

Low dose dexamethasone suppression test - how does it work and what is normal result?

Answer 6

1mg Dex at 2300
Plasma cortisol at 0800
Normal suppressionq to less than 50

Question 7

Suspected Cushing’s - what is the test of choice in pregnancy?

Answer 7

Urinary free cortisol (don’t use dexamethasone suppression test)

Question 8

Suspected Cushing’s - what is the test of choice in epilepsy?

Answer 8

Use non-suppressed levels. Antiepileptics can clear Dex faster.

Question 9

Suspected Cushing’s - what is the test of choice in renal failure?

Answer 9

1mg overnight dex suppression test (not UFC)

Question 10

Suspected Cushing’s - what is the test of choice in adrenal incidentaloma?

Answer 10

Dex suppression test or late night cortisol (not UFC)

Question 11

Cushing’s syndrome - treatment?

Answer 11

Pituitary surgery first line (or can irradiate)

Bilateral adrenalectomy second line

Question 12

Cushing’s syndrome - best evidence of cure post-op?

Answer 12

Hypocortisolism

Question 13

Diabetes insipidus - investigations?

Answer 13

Water deprivation test to determine ability to concentrate urine

ddAVP to determine central (responds by concentrating urine) versus nephrogenic (doesn’t respond)