In addison's disease, most diagnostic test is:

Answer is D (ACTH stimulation test): The diagnosis of Adrenal insufficiency should be made only Hith A C'TH stimulation testing - Harrison's ACTH stimulation test / Cosvntropin stimulation test Synthetic ACTH (Cosyntropin) is given parentrally in a dose of 250 tg (or 0.25 mg) Serum is obtained for coisol between 30 to 60 minutes after Cosyntropin is administered Coisol levels should be greater than 495 mmol/L (> 18pg/dL) Coisol levels >495 exclude the diagnosis of Addison's disease while coisol levels < 495 suggest a possible diagnosis of Adrenal insufficiency (primary or secondary).