This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': "In Addison's disease, the most diagnostic test is - \nSelect and explain. \nA. Serum Na+,K+ renin, B. S. Na+,K+, saline suppression, C. Serum creatinine/urea ratio, D. ACTH stimulation test", 'role': 'user'}, {'content': 'Answer: D \nExplanation: The best method used for diagnosis of adrenal insufficiency is ACTH stimulation test.\n\nAddison\'s disease is produced due to deficiency of serum cortisol, but the measurement of these hormones is not the best way to diagnose addison\'s disease.\nAddison\'s disease is best diagnosed by ACTH stimulation test.\n\n\nThe ACTH stimulation test detects the adrenal deficiency at very early stage of addisons disease when serum cortisol levels are normal.\nDuring the early phase of addison\'s disease, the serum cortisol levels are normal, but the adrenal reserve is decreased.\nDuring these phases the adrenal deficiency is precipitated by stress.\nACTH stimulation can expose the cortisol deficiency even at these stages\n\n\xa0"Upon ACTH stimulation the increase in cortisol level is less than normal."\n\nACTH stimulation test is performed by assessing cortisol response upon administering 250 IV of consyntopin\xa0 i.v. or i.m. \nThe criteria for normal response is serum cortisol level >500 nmol/l (>18 µg/d1).\nIf the response is subnormal addison\'s disease is diagnosed.\nTo further differentiate between primary and secondary addison\'s disease, serum aldosterone level is measured from the same serum sample.\n\nSerum aldosterone\n\nPrimary addison\'s disease\xa0\xa0\xa0 → Decreased\nSecondary addison\'s disease\xa0\xa0\xa0 →\xa0\xa0\xa0\xa0 Normal', 'role': 'assistant'}]