Medicine Which of the following tests is best for differentiating ACTH secreting pituitary tumour from Ectopic ACTH production? A 24 hour Urinary free coisol B Overnight dexamethasone suppression test C Low dose dexamethasone suppression test D High dose dexamethasone suppression test 💡 Explanation Which of the following tests is best for differentiating ACTH secreting pituitary tumour from Ectopic ACTH production? ✓ Correct Answer: D. High dose dexamethasone suppression test