Cushings

Question 1

What’s the thrust of cushing’s?

Answer 1

-hypercortisolaemia

Question 2

What are the causes of increased circulating cortisol?

Answer 2

• prolonged steroids
• pituitary ACTH secreting tumour
• adrenal adenoma
• ectopic ATCH - SCLC paraneoplastic

Question 3

What are the symptoms of cushing’s?

Answer 3

• Skin changes - bruising easily, acne, hirsutism, hyperpigmentation, purple abdo striae (stretch marks)
• neuropsych - depression, lethargy
• MSK - osteopenia, osteoporosis
• Endocrine:
  
  • weight gain = MOON FACE, buffalo hump
  • insulin resistance = Sx hyperglycaemia
  • decreased libido
  • irregular periods
• HTN

Question 4

What test’s can you do to confirm hypercortisolaemia?

Answer 4

• 24hr urinary cortisol (3x the upper limit)

- morning serum cortisol following low-dose dexamethosone test

Question 5

How do you localise the cause of cushing’s?

Answer 5

• low/high dose dexamethasone test:
  
  • in normal patients dexamethasone suppresses ACTH production & thus cortisol levels
  • in cushing’s cortisol don’t change post test due to abnormal production*

*cortisol may decrease in cushing’s disease (pituitary tumour) because it’s ATCH dependent

Question 6

Other than the dexamethasone suppression test, what other investigations would you do for cushing’s?

Answer 6

• MRI head

- CT chesst/abdo/pelvis

Question 7

What’s the management for cushing’s?

Answer 7

• reduce dose of steroids
• change steroids to other immunosuppressant drugs i.e. azothioprine
• surgical removal of tumour
• drugs to suppress cortisol - metyrapone

Question 8

What electrolyte abnormalities can cushing’s cause? and Why?

Answer 8

• hypernatremia
• hypokalaemia
• alkalosis

free cortisol binds to renal mineralcorticoid recpetors and causes increase water and sodium retention + increase potassium and hydrogen ion excretion