Confirmatory Serum Testing for Addison Disease

Plasma ACTH

High (≥ 50 pg/mL [≥ 11 pmol/L])

Serum cortisol

Low (< 5 mcg/dL [< 138 nmol/L])

ACTH stimulation test

Subnormal (ie, 30-minute cortisol should be < 15–18 mcg/dL [< 414–497 nmol/L], according to the assay)

Prolonged (24-hour) ACTH stimulation test

Cortisol should be subnormal at 1 hour and should not rise further at 24 hours