Serum uric acid and arterial lactate levels in patients with obstructive sleep apnea syndrome: the effect of CPAP treatment

Abstract

ABSTRACT Objectives: Serum uric acid (UA) and arterial lactate acid (LA) are markers of oxidative stress and tissue hypoxia that are present in patients with obstructive sleep apnea syndrome (OSAS). The aim of the study was to evaluate the associations between UA and LA levels and OSAS characteristics as well as the effect of their levels after continuous positive airway pressure (CPAP) treatment. Methods: This is a retrospective of newly diagnosed patients with OSAS. UA and LA levels were measured the night before the diagnostic sleep study, and 6 months after CPAP therapy. Results: We evaluated 604 individuals with OSAS and 98 controls (i.e. individuals without sleep-related breathing disorders). Baseline median (IQR) serum UA levels were higher in OSAS patients compared to controls; 7.0 (6.4, 8.1) mg/dL vs 6.3 (6.1, 6.4) mg/dL, respectively (p < 0.001). This difference remained significant, after adjustment of serum UA to creatinine ratio (UA/Cr) (p < 0.001). Patients with OSAS had higher LA levels at baseline compared to controls; 2.26 (2.25, 2.31) mmol/L vs 1.90 (1.87, 1.97) mmol/L, respectively (p < 0.001). Both UA and LA levels decreased significantly after CPAP treatment [median (IQR): 7.0 (6.4, 8.1) mg/dL vs 6.4 (6.2, 6.8) mg/dL, p < 0.001 and 2.26 (2.25, 2.31) mmol/L vs 2.08 (2.07, 2.31) mmol/L, p < 0.001]. Several sleep parameters were independent predictors of UA and LA levels. Conclusion: In OSAS patients increased serum UA and arterial LA levels are found. CPAP therapy resulted in significant reductions in levels of both biomarkers.