Endocrine Investigations

Question 1

Hypopituitarism

Answer 1

9am ACTH, 9am cortisol
TSH, Free T3/T4
FSH/LH, E2 or 9am Testosterone
IGF-1
Prolactin
Plasma/urine osmolality

Synacthen test
Insulin stress test/ prolonged glucagon test
Water deprivation test

Imaging/ Aetiology focused tests

Question 2

Diabetes insipidus

Answer 2

Plasma/urine osmolality
Water deprivation test
(& check for improvement with DDAVP)
If CDI => Imaging e.g. MRI

Question 3

Acromegaly

Answer 3

Serum IGF-1
Insulin stress test/ prolonged glucagon test

Question 4

Hyperprolactinaemia

Answer 4

Serum prolactin
Aetiology tests e.g. primary hypothyroidism, pituitary tumour

Question 5

Pituitary adenoma

Answer 5

MRI brain
Visual field test
Hormone tests e.g. serum prolactin

Question 6

Hypothyroidism & Hyperthyroidism

Answer 6

TSH, Free T3/T4
Anti-TPO, TRAb
Scintiscan

Question 7

Follicular adenoma & carcinoma
Papillary adenoma

Answer 7

Serum TSH
USS-FNA (cannot distinguish between adenoma & carcinoma)
Lobectomy & biopsy (definitive)

Question 8

Summarise the synacthen test & state when it is used

Answer 8

• Check cortisol at 0, 30 and 60 mins
• Normal: cortisol rises by 150 and reaches 500
• Used to test for cortisol deficiency i.e.
  Addison’s/primary adrenal insufficiency

Question 9

Summarise the insulin stress test/prolonged glucagon test & state when it is used

Answer 9

• Cortisol and GH response every 30 min for 2-3 hours
• Normal cortisol >500
• Normal GH >7ug/l
• Used to test for GH & cortisol deficiency

Question 10

Summarise the water deprivation test & state when it is used

Answer 10

• Check serum and urine osmolarities for 8hr, and then 4hr after giving IM DDAVP
• If Ur/serum osmol ratio >1.9 then it is normal, otherwise DI
• Used to test for AVP deficiency