Cushings Syndrome

Question 1

Cushings Syndrome:

Cortisol homeostasis?

Answer 1

1) Hypothalamus - Corticotropin Releasing Hormone (CRH)
2) Anterior pituitary - Adrenocorticotropic Hormone (ACTH)
3) Adrenal gland - Cortisol and Aldosterone

With negative feedback loops

Question 2

Cushings Syndrome:

What is Cushings Syndrome and the symptoms/features?

Answer 2

Endogenous or Exogenous excess of cortisol
20 - 50yo
F > M

CUSHING
Central obesity, cushingnoid - moon face, buffalo hump, clavicular fat pad
Urinary free cortisol
Stria, Suppressed immunity
Hypertension, hyperglycaemia, hyperlipidaemia, Hirsutism, Hyperpigmentation
Irritability
Neoplasia - linked to MEN1
Glucose intolerance

Question 3

Cushings Syndrome:

Causes?

Answer 3

1) Pituitary tumour = high ACTH and high cortisol
2) Adrenal tumour = high cortisol independent of ACTH
3) Adrenal nodular hyperplasia
4) Ectopic ACTH or CRH producing tumour

*is linked to MEN1

Question 4

Cushings Syndrome:

investigation?

Answer 4

1) Confirm cortisol abnormally elevated
- 24hr urinary cortisol
- saliva cortisol at 9am and midnight (normal is elevated morning and low midnight cortisol)
- 1mg Dexamethasone overnight (1mg at 2300hrs then test morning serum cortisol - abnormal if elevated)

2) Check origin of cortisol
- 9am serum ACTH (if elevated - this suggests ectopic CRH/ACTH/pituitary tumour, low suggests cortisol has an adrenal source)

IF ectopic ACTH/CRH suspected - radiolabelled ocreotide scan (localises at lesion site)

If pituitary or adrenal tumour suspected - MRI brain/adrenals