Abstract P273: Association Between 24-hr Urinary Cortisol and Severity of Obstructive Sleep Apnea in Patients With Resistant Hypertension

Abstract

Background: Plasma cortisol levels have been found to be negatively associated with severity of obstructive sleep apnea (OSA) based on morning salivary cortisol levels. Studies on pediatric patients have suggested that salivary cortisol can be used as a biomarker for assessment of OSA severity and to analyze prognosis following treatment with continuous positive airway pressure (CPAP). We hypothesized that 24-hr urinary cortisol levels are associated with severity of OSA in patients with resistant hypertension (HTN). Methods: In this prospective study, 197 patients were recruited from University of Alabama at Birmingham resistant HTN clinic. Office blood pressure (BP), diagnostic polysomnogram (PSG), 24-hr urine analysis for cortisol were done in these patients as part of study protocol. Patients with a diagnosis of OSA who were already treated with CPAP were excluded. Results: Out of 116 patients who were analyzed based on inclusion criteria, 53.5% were female, 62.1% were African American and the mean baseline values were age 57.4 ± 10.6 in years, body mass index 34.9 ± 7.4 kg/m 2 , 24-hr urinary cortisol 12.1 ± 7.7 mcg, apnea-hypopnea index (AHI) 9.4 ± 13.0 events/hr. Regression analysis was done between 24-hr urinary cortisol and AHI, and the Pearson correlation coefficient was 0.0498 (p = 0.602). There was no significant correlation between 24-hr urinary cortisol level and increasing AHI. Conclusion: In this cross-sectional study, 24-hr urinary cortisol level was not significantly associated with increasing AHI, indicating that 24-hr urinary cortisol may not play a role in the severity of OSA in patients with resistant HTN.