Ironside N, et al. - Physicians designed this study to evaluate whether the delay in reaching post-operative cortisol nadir could delineate those at risk of recurrence for Cushing's disease (CD) following transsphenoidal surgery (TSS). For durable remission, profound hypocortisolemia could be used as a clinical prediction tool. As per the outcomes, achievement of hypocortisolemia ≤ 2 μg/dL before 21 post-operative hours appeared to accurately predict durable remission.