Cushing's Syndrome

Question 1

What is Cushing’s syndrome?

Answer 1

The signs and symptoms that develop after prolonged abnormal elevation of cortisol

Question 2

What is Cushing’s disease:

Answer 2

The specific condition where a pituitary adenoma secretes excessive ACTH causing a Cushing’s syndrome

Question 3

What does excessive ACTH cause?

Answer 3

Excess cortisol levels

Question 4

Which gland is Cushing’s a disease of?

Answer 4

Pituitary or adrenal gland

Question 5

What are some Cushing’s syndrome features?

Answer 5

Round “moon” face
Central obesity
Abdominal striae
Buffalo jump (fat pad on upper back)
Proximal limb muscle wasting
Easy bruising
Osteoporosis

Question 6

What does high cortisol levels cause?

Answer 6

Hypertension
Cardiac hypertrophy
Hyperglycaemia (T2DM)
Depression
Insomnia

Question 7

What are the causes of Cushing’s syndrome?

Answer 7

Cushing’s disease- pituitary adenoma

Ectopic ACTH secretion- excess ACTH released from a cancer not of the pituitary

Adrenal adenoma- hormone secreting adrenal tumour

Glucocorticoid treatment

Question 8

What is the most common cause of Cushing’s syndrome?

Answer 8

Glucocorticoid treatment (iatrogenic)

Question 9

What investigations are done for Cushing’s?

Answer 9

24hr urinary free cortisol
1mg overnight dexamethasone suppression test
Low dose dexamethasone test
High dose dexamethasone test
MRI brain for pituitary adenoma
Chest CT for SCLC
Abdominal CT for adrenal tumours

Question 10

What is low dose dexamethasone test?

Answer 10

• Patient takes dexamethasone at night and their cortisol and ACTH are measured in the morning
• Normal response is for dexamethasone to suppress cortisol release by effecting negative feedback on the hypothalamus and pituitary
• Hypothalamus reduced CRH output and pituitary reduced ACTH output
  A high or normal cortisol suggests Cushing’s syndrome

Question 11

What is high dose dexamethasone test?

Answer 11

Performed after abnormal low dose test results
- Low cortisol levels indicate pituitary adenoma
- High cortisol but low ACTH indicate adrenal adenoma because cortisol production is independent from the pituitary
- High cortisol and high ACTH indicated ectopic ACTH

Question 12

What is the treatment of Cushing’s disease (pituitary adenoma)?

Answer 12

Trans-sphenoidal removal of pituitary adenoma

Question 13

What is the treatment of Adrenal Cushing’s?

Answer 13

Surgical removal of adrenal ACTH

Question 14

What is the treatment of ectopic ACTH?

Answer 14

Surgical removal of tumour producing ectopic ACTH