Relationship Between Serum Uric Acid Levels and Sleep-Related Breathing Disorders in Obese Subjects

Abstract

Objective: We examined the serum uric acid (UA) levels among patients with sleep-related breathing disorders (SRBD) and the relationship between UA levels and obstructive sleep apnea (OSA) severity, nocturnal hypoxemia (NH) and obesity hypoventilation syndrome (OHS).Material and Method: Subjects with body mass index (BMI) ≥30 kg/m 2 who, according to polysomnography results, have SRBD were included. Demographics, anthropometric measurements and serum UA were recorded. The apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) were recorded. The OSA severity was graded as mild (AHI 5-14 events/hour), moderate (AHI 15-29 events/hour) or severe (AHI ≥30 events/hour). NH was considered when sleep time spent with SpO 2 <90% was ≥30%. PaCO 2 >45 mmHg was considered OHS. Results:The study included 159 patients with SRBD (79 female, 80 males, age: 50.0±10.5 years, BMI: 40.1±5.7 kg/m 2 ). Seventy-six had OHS and 83 had pure OSA. NH was detected in 25.8% of patients. UA levels were higher in subjects with NH (6.22±1.37 mg/dl, 5.67±1.51 mg/dl, p=0.008). UA levels were similar in patients with OHS and pure OSA (5.91±1.25 mg/dl, 5.72±1.68 mg/ dl, p=0.1). UA levels increased as OSA severity increased (mild: 5.03±1.41 mg/dl, moderate: 5.46±1.55 mg/dl, severe: 6.19±1.8 mg/dl, p=0.039). UA levels were higher in males with OSA (6.86±1.64 mg/dl, 4.84±1.10 mg/dl, p<0.001). UA levels were correlated with neck circumference (r=0.366, p<0.001), waist/ hip ratio (r=0.358, p<0.001), OSA severity (r=0.224, p=0.005), AHI (r=0.250, p=0.001), ODI (r=291, p<0.001) and sleep time with SpO 2 <90% (r=0.228, p=0.004). Male gender, waist/hip ratio and NH were factors independently related with UA levels (retrospectively; p<0.001, p=0.03, p=0.03). Conclusion:In obese subjects with SRBD, serum UA levels were associated with male gender, NH and OSA severity.