This assay is used to determine the cause of Hypocortisolism & Hypercortisolismstates. In a patient with hypocortisolism, an elevated ACTH indicates Primaryadrenal insufficiency whereas normal levels are consistent with secondary adranalinsufficiency from pituitary or hypothalamic causes. In a patient of hypercortisolism(Cushing's syndrome), a suppressed value is consistent with Cortisol producingAdrenal adenoma/carcinoma, Primary adrenal micronodular hyperplasia &Exogenous corticosteroid use.