Surgical success is confirmed by subnormal levels of early morning serum cortisol measured within a few days of surgery. Typically, early morning serum cortisol levels of either <2 µg/dL (~50 nmol/L) or <5 µg/dL within a few days after surgery are considered to be indicative of remission [3]. However, reported results are mixed and difficult to interpret since some studies measure basal serum cortisol levels while others use serum cortisol following dexamethasone suppression, or some combination of these measures [5, 11–13]. While clinical practice guidelines provide recommendations for testing in the context of initial diagnosis of CD [10], there is no expert consensus with regard to post-operative testing for surgical success.