Cushings syndrome

Question 1

What are some ACTH dependent causes

Answer 1

Cushings disease -80%
- pituitary tumour secreting ACTH producing adrenal hyperplasia

Ectopic ACTH production- 5-10%
small cell lung cancer most common cause

Question 2

What are some ACTH independent causes

Answer 2

Iatrogenic - steroids
adrenal adenoma
adrenal carcinoma ( rare)
Carney complex
Micronodular adrenal dysplasia - very rare

Question 3

What is Pseudo- Cushings

Answer 3

mimics cushing’s
often due to alcohol excess/severe depression

causes false positive dexamethasone suppression test /24hr urinary free cortisol

Insulin stress test can be used to differentiate

Question 4

What are key diagnostic factors of Cushings syndrome

Answer 4

facial plethora
supraclavicular fullness
violaceous striae
menstrual irregularities

absence of pregnancy , malnutrition, alcoholism and physiological stress

Question 5

What are other symptoms of Cushing’s syndrome

Answer 5

hypertension
glucose intolerance /DM
premature osteoporosis/ unexplained fractures

weight gain and centripetal obesity

acne

decreased libido

easy bruising

Question 6

What investigations are required

Answer 6

Overnight 1 mg dexamethasone suppression test
– morning cortisol not suppressed

24hr urinary free cortisol

Question 7

What are some specific investigations to find out the exact cause of Cushings

Answer 7

9am and midnight ACTH levels
- if ACTH suppressed at night then , non-dependent ACTH cause is likely

Question 8

What do certain results of the high dose dexamethasone suppression test mean

Answer 8

Cortisol not suppressed but ACTH is suppressed- Cushing’s syndrome is due to causes such as adrenal adenomas

If Cortisol and ACTH both suppressed- Cushing’s disease – pituitary adenoma

If cortisol and ACTH both not suppressed - ectopic ACTH syndrome

Question 9

What are some other investigations to consider

Answer 9

Pituitary MRI if ACTH dependent
Adrenal CT if ACTH independent

Insulin stress test to differentiate between true psuedo-Cushing’s

Question 10

What is management for Cushings disease/ pituitary adenoma

Answer 10

transsphenoidal pituitary adenomectomy

Question 11

What is management for ectopic ACTH/CRH syndrome

Answer 11

surgical resection/ablation of tumour and metastases

Question 12

What is management for unilateral adrenal carcinoma/adenoma

Answer 12

unilateral adrenalectomy / tumour resection

Question 13

What would you see ABG wise in a person with cushings syndrome

Answer 13

hypokalemic metabolic alkalosis

along with impaired glucose tolerance