A 40-year-old man with signs of Cushing's syndrome has elevated cortisol not suppressed by low-dose dexamethasone. Which test is next to differentiate...

Question

A 40-year-old man with signs of Cushing's syndrome has elevated cortisol not suppressed by low-dose dexamethasone. Which test is next to differentiate Cushing's disease (pituitary) from ectopic ACTH or adrenal causes?

Accepted Answer

High-dose dexamethasone suppression test

Answer

MRI adrenals

Answer

Late-night salivary cortisol

Answer

Plasma aldosterone-to-renin ratio

Answer

Insulin tolerance test

Cushing's syndrome — MRCP Part 1 MCQ

A 40-year-old man with signs of Cushing's syndrome has elevated cortisol not suppressed by low-dose dexamethasone. Which test is next to differentiate Cushing's disease (pituitary) from ectopic ACTH or adrenal causes?