Diagnosis Adrenal Insufficiency - Algorithm Step 1) Screening Test: 6-8AM Cortisol Level - Early morning cortisol levels < 5 have almost 100% specificity for AI (but low sensitivity). - Levels > 15 excludes AI in almost all patients, though some use a cutoff of > 18. - Intermediate levels (5 – 15), require Cosyntropin testing. Step 2) Confirmation Test: Cosyntropin Stimulation - Cosyntropin is an ACTH analogue. This test determines if the adrenal gland appropriately responds to a bolus of ACTH. - Check ACTH before administering cosyntropin (IV 250mcg). Then, check cortisol 30 min AND 60 min after administration. - Peak cortisol level should be > 18. If it is lower, you have diagnosed AI. Step 3) Differentiate primary vs secondary AI (by looking at the ACTH level checked in Step 2 above). - Low ACTH is consistent with secondary (i.e. problem with pituitary gland) - High ACTH is consistent with primary (i.e. problem with adrenal gland) #Adrenal #Insufficiency #Algorithm #Diagnosis #ACTH #Stimulation #Endocrinology