New Cutoffs for the Biochemical Diagnosis of Adrenal Insufficiency after ACTH Stimulation using Specific Cortisol Assays

To reduce false positive ACTH stimulation testing, we recommend a new serum cortisol cutoff of 14 to 15 μg/dL depending on the assay used (instead of the historical value of 18 μg/dL with older polyclonal antibody assays). Clinicians should be aware of the new cutoffs for the assays available to them when evaluating patients for AI.