Condition
Cushingís syndrome:cortisol excess (cont)
Metyrapone test: cortisol levels are normal to increased in pituitary Cushingís, but there is no change in adrenal or ectopic Cushingís.
Clonidine suppression test: release of catecholamines in pheochromocytoma is autonomous and not susceptible to manipulation by clonidine, an a2-agonist that decreases efferent sympathetic outflow.
Isotonic saline infusion: isotonic saline should suppress aldosterone release by decreasing release of renin. Lack of suppression of aldosterone indicates primary aldosteronism.