Cushing's syndrome

Question 1

Cushing’s Syndrome

Answer 1

Chronic glucocorticoid excess - cortisol

Question 2

Features

Answer 2

Catabolic Effects:
Proximal myopathy
Striae
Bruising
Osteoporosis

Glucocorticoid Effects:
DM
Central Obesity

Mineralocorticoid Effects:
HTN
Hypokalaemia

Question 3

Cushingoid Appearance

Answer 3

Moon face
Acne and hirsutism
Interscapular and supraclavicular fat pads - buffalo hump 
- Central obesity with thin extremities
- Striae
- Bruising and thin skin

Question 4

ACTH-Independent

Answer 4

↓ACTH due to –ve feedback

No suppression with any dose of dexamethasone

Question 5

Causes of ACTH independent Cushing’s

Answer 5

Iatrogenic steroids: commonest cause
Adrenal adenoma / Ca: carcinoma
Adrenal nodular hyperplasia

Question 6

ACTH-Dependent

Answer 6

↑ ACTH

Question 7

Causes of ACTH-Dependent Cushings

Answer 7

Cushing’s disease

Ectopic-ACTH

Question 8

Cushing’s disease

Answer 8

Bilateral adrenal hyperplasia from ACTH-secreting
pituitary tumour

Mx: Cortisol suppression with high-dose dexamethasone

Question 9

Ectopic-ACTH

Answer 9

• Small cell lung carcinoma
• Carcinoid tumour

Presents with:

• Skin pigmentation - MSH
• metabolic alkalosis
• wt. loss
• hyperglycaemia

No suppression c¯ any dose of dex

Question 10

Ix

Answer 10

1. 24h urinary free cortisol
2. Late night serum or salivary cortisol
   - Highest in the morning
   - Lowest at midnight
3. Dexamethasone suppression tests
   - ACTH
4. CT/ MRI
5. DEXA scan

Question 11

Tx of Cushing’s syndrome

Answer 11

Treat Cause

• Cushing’s disease: trans-sphenoidal excision
• Adrenal adenoma / Ca: adrenelectomy
• Ectopic ACTH: tumour excision