<prompt> In Addisons disease, the most diagnostic test is -Serum Na,K reninS. Na,K, saline suppressionSerum creatinineurea ratioACTH stimulation test  <response>: The best method used for diagnosis of adrenal insufficiency is ACTH stimulation test.Addisons disease is produced due to deficiency of serum cortisol, but the measurement of these hormones is not the best way to diagnose addisons disease.Addisons disease is best diagnosed by ACTH stimulation test.The ACTH stimulation test detects the adrenal deficiency at very early stage of addisons disease when serum cortisol levels are normal.During the early phase of addisons disease, the serum cortisol levels are normal, but the adrenal reserve is decreased.During these phases the adrenal deficiency is precipitated by stress.ACTH stimulation can expose the cortisol deficiency even at these stages Upon ACTH stimulation the increase in cortisol level is less than normal.ACTH stimulation test is performed by assessing cortisol response upon administering 250 IV of consyntopin i.v. or i.m. The criteria for normal response is serum cortisol level 500 nmoll 18 μgd1.If the response is subnormal addisons disease is diagnosed.To further differentiate between primary and secondary addisons disease, serum aldosterone level is measured from the same serum sample.Serum aldosteronePrimary addisons disease DecreasedSecondary addisons disease Normal 