Cushings syndrome

Question 1

What is cushings syndrome?

Answer 1

chronic inappropriate elevation of free circulating cortisol

Question 2

What is ACTH dependent Cushing’s syndrome?

Answer 2

80% = Excess ACTH from pituitary adenoma: Cushing's disease   
20% = Ectopic ACTH e.g. small cell lung cancer or carcinoid tumour

Question 3

What causes excess cortisol secretion in ACTH independent Cushing’s syndrome?

Answer 3

Benign adrenal adenoma

Adrenal carcinoma

Question 4

Name a rare cause of Cushing’s syndrome

Answer 4

ACTH independent micro or macro nodular adrenal hyperplasia

Question 5

Describe the epidemiology of Cushing’s syndrome

Answer 5

Incidence: 2-4 / 1,000,000 per year
F > M
Peak incidence 20-40 yrs

Question 6

List 6 symptoms of Cushing’s syndrome

Answer 6

Weight gain
Fatigue  
Myalgia  
Proximal muscle weakness      
Oligomenorrhoea/ amenorrhoea 
Depression or psychosis

Question 7

List 13 signs of cushings syndrome

Answer 7

Round face (Moon face) 
Facial plethora (Red Cheeks)
Interscapular fat pad (Buffalo Hump) 
Central obesity
Striae on abdomen/breast/thighs 
Thin skin 
Thin arms + legs 
Easy bruising, poor wound healing 
Fractures
Hirsuitism, acne, frontal balding  
HTN
Ankle oedema (salt + water retention as mineralocorticoid effect of excess cortisol) 
Pigmentation (in ACTH dependent)

Question 8

What bloods are performed in Cushing’s syndrome?

Answer 8

U+Es: hypokalaemia due to mineralocorticoid effect

BM: high glucose

Question 9

What initial high sensitivity tests should be performed in Cushings syndrome?

Answer 9

1st: Overnight dexamethasone suppression test
Urinary free cortisol
2nd: Low dose dexamethasone suppression test

Question 10

What tests should be performed to determine the underlying cause of ACTH independent Cushing syndrome?

Answer 10

Plasma ACTH LOW

CT or MRI of adrenals

Question 11

If lung cancer is the suspected cause of Cushing’s syndrome, what investigations should be performed?

Answer 11

CXR, sputum cytology, bronchoscopy, CT san

Radiolabelled octreotide scans can detect carcinoid tumours as they express somatostatin receptors

Question 12

How is cushings managed when the cause is iatrogenic?

Answer 12

Discontinue steroids

Use lower dose steroid or steroid-sparing agent

Question 13

What is the medical management of cushings syndrome?

Answer 13

Used pre-operatively/ if unfit for surgery
Metyrapone or ketoconazole to inhibit cortisol synthesis
Treat osteoporosis
Physiotherapy for muscle weakness

Question 14

What surgical treatments can be performed in Cushings syndrome?

Answer 14

Pituitary Adenomas: trans-sphenoidal adenoma resection
Adrenal adenoma/carcinoma: removal of tumour
Ectopic ACTH: tx directed at the tumour

Question 15

List 4 complications of Cushing’s syndrome

Answer 15

Diabetes
Osteoporosis
HTN
Pre-disposition to infections

Question 16

List 4 complications of surgery for cushings syndrome

Answer 16

CSF leakage
Meningitis
Sphenoid sinusitis
Hypopituitarism

Question 17

List 3 complications of radiotherapy for cushings syndrome

Answer 17

Hypopituitarism
Radionecrosis
Increased risk of 2nd intracranial tumours
+ stroke

Question 18

What is the prognosis in Cushings syndrome?

Answer 18

Untreated: 5 yr survival = 50%

Depression persists for many years following tx

Question 19

What tests should be performed to determine the underlying cause of ACTH dependent Cushing syndrome?

Answer 19

Plasma ACTH HIGH
Pituitary MRI
High-dose dexamethasone suppression test
Inferior petrosal sinus sampling, Central: peripheral ratio of venous ACTH > 2:1 in Cushing’s disease

Question 20

When is radiotherapy performed in Cushings syndrome?

Answer 20

Performed in those who are not cured + have persistent high cortisol after trans-sphenoidal resection of the tumour