Cushing's syndrome

Question 1

Issue

Answer 1

glucocorticoid excess

Question 2

Causes

Answer 2

Adrenocorticotropic hormone (ACTH)-dependent disease:
-Cushing’s disease (80%): pituitary tumour secreting ACTH producing adrenal hyperplasia
ectopic ACTH production (5-10%): e.g. small cell lung cancer is the most common causes

Non-ACTH dependent:
- iatrogenic: STEROIDS
- adrenal adenoma (5-10%)
- adrenal carcinoma (rare)
- Carney complex: syndrome including cardiac myxoma
- micronodular adrenal dysplasia (very rare)

Question 3

Features (STRESSED)

S-Skin […]
T-Truncal […] with small arms.
R- […] face - […] […]
E- […], Elevated blood pressure.
S-[…] on the extremities and […] ([…])
S-[…] extremely high.
E-Excessive […] […] especially in women, Electrolytes imbalance: […].
D-[…] fat pad (Buffalo hump), […].

Answer 3

fragile.
obesity
Rounded, moon facies
Ecchymosis
Striae, abdomen (Purplish)
Sugar
body hair, hypokalemia.
Dorsocervical, Depression.

Question 4

Acid base picture

Answer 4

hypokalaemic metabolic alkalosis

• Cortisol acts on kidneys to excrete potassium and retain sodium

Question 5

Invx

Answer 5

Low-dose Dexamethasone suppression test - patients with Cushing’s syndrome do not have their morning cortisol spike suppressed
24hr urinary free cortisol

Question 6

Localisation (ACTH-dependent vs non-ACTH-dependent origin)

Answer 6

1. first-line localisation is 9am and midnight plasma ACTH (and cortisol) levels.

If ACTH is suppressed then a non-ACTH dependent cause is likely such as an adrenal adenoma

High-dose dexamethasone suppression test

Question 7

Localisation

Answer 7

See passmed

Question 8

Management
Medical
- […] –> steroid synthesis pathway […]
Others […] (adrenolytic agent), […] (glucocorticoid antagonist)

Surgical (Cushing’s disease) –> […] […] + LT […] […]

Answer 8

Medical
Metyrapone, blocker
Ketoconazole, Mifepristone
transsphenoidal addenectomy, steroid replacement