Despite the large number of long-term follow-up studies published, no single positive predictive factor of recurrence has emerged. Although subnormal levels of early morning serum cortisol levels measured within a few days following surgery suggest a lower risk of recurrence, relapse does occur in approximately 9 % of patients in this population [40]. Patients who achieve normal, but not subnormal post-surgical levels of cortisol are at a higher risk for recurrence (~24 %), although many of these patients may experience long-term remission [40]. Evaluation of the HPA axis in addition to cortisol levels may provide an advantage, but results to date are contradictory and further studies are needed. Since there is no fail-safe predictor of recurrence, standardized lifelong monitoring of post-surgical patients with CD is recommended for timely detection and optimal treatment of disease recurrence.