Cushing's syndrome

Question 1

What is cushing’s syndrome

Answer 1

Clinical state produced by glucocorticoid excess. Loss of normal feedback mechanisms and loss of circadian rhythm of cortisol secretion

Question 2

What are causes of cushing’s syndrome?

Answer 2

ACTH dependent (increased)

Cushing’s disease (pituitary tumour secreting ACTH), bilateral adrenal hyperplasia, ectopic ACTH or CRH

ACTH independent (low)

Iatrogenic steroid use, adrenal adenoma or carcinoma

Question 3

What are Sx of Cushing’s?

Answer 3

Weight gain and central obesity, facial plethora, striae, thin skin and proximal muscle weakness, easy bruising, acne

Metabolic complications include DM, OP, hypertension

Question 4

What Ix in Cushing’s?

Answer 4

Cortisol testing e.g. 24 hour urinary free cortisol (increased), dexamethasone suppression test, late nigh salivary cortisol (will be high), CRH test

Hypokalaemic metabolic alkalosis may be seen

Impaired glucose tolerance

Imaging: adrenal CT or MRI, pituitary MRI (often microadenoma and can’t see), CTCAP if ectopic ACTH source

Question 5

What is Rx of Cushing’s disease?

Answer 5

If iatrogenic, stop the steroids

If pituitary, transsphenoidal removal of the tumour or radiotherapy

If adrenal, laparoscopic adrenalectomy and steroid replacement after

If ectopic, surgery if located

Metyrapone, ketoconazole/fluconazole can decrease cortisol secretion pre-op