Post-operative Day One Morning Cortisol Value as a Biomarker to Predict Long-term Remission of Cushing Disease.

CONTEXT Recurrence of Cushing disease (CD) can occur even decades after surgery. Biomarkers to predict recurrence of CD after surgery have been studied but are inconclusive. OBJECTIVE The aim of our study was to identify specific biomarkers that can predict long-term remission after neurosurgery. DESIGN Identification of specific biomarkers to predict long-term remission of CD was performed by logistic regression analysis followed by Kaplan-Meier survival analysis, using recurrence as the dependent variable. SETTING 260 patients with CD identified from our institutional research patient data registry search tool and from patients who presented to our longitudinal multidisciplinary clinic between May 2008 and May 2018 underwent statistical analysis. INTERVENTIONS Data on clinical features, radiographs, pathology, biochemistry, treatments were collected by reviewing digital chart records. MAIN OUTCOME MEASURE Post-operative (post-op) cortisol as a biomarker to predict long-term remission after surgical treatment for CD. RESULTS By logistic regression analysis, post-op day one (POD1) morning (5-10 AM) serum cortisol, female sex and proliferative index had significant association with CD recurrence (OR=1.025, 95% CI:1.002-1.048, p=0.032). In contrast, the post-op nadir cortisol (OR=1.081, 95% CI:0.989-1.181, p=0.086), urinary free cortisol (OR=1.032, 95% CI:0.994-1.07, p=0.098) and late night salivary cortisol (OR=1.383, 95% CI:0.841-2.274, p=0.201) had no significant correlation with recurrence. A significant association between POD1 morning serum cortisol and long-term CD remission was verified by Kaplan-Meier analysis when using POD1 morning serum cortisol < 5 μg/dL as the cut-off. CONCLUSIONS The POD1 morning serum cortisol level has a significant association with CD recurrence.