A 34 year old woman presents with truncal obesity, easy bruising, hyperglycemia, high BP and depression. Which of the following investigation will be most helpful in localizing the cause for Cushing’s syndrome?

The key is D. High dose dexamethasone suppression test. [High dose dexamethasone suppression

test can identify whether pituitary adenoma or ectopic ACTH producing tumour. Suppression is absent in

patients with Cushing syndrome due to ectopic ACTH secretion or adrenal abnormalities. Suppression is

present in patients with Cushing disease].