Elevated Serum Markers of Acute Kidney Injury in Patients With Obstructive Sleep Apnea

Abstract

Study Objectives: Previous research revealed a positive correlation between endothelial cell injury (indicated by albuminuria) and obstructive sleep apnea (OSA). However, little else has been revealed about acute kidney injury (AKI) in patients with OSA. Methods: This prospective study recruited consecutive patients undergoing overnight polysomnography for evaluation of sleep apnea. Patients in whom any major disease or recent infection had been previously diagnosed were excluded. Ultimately, data from 75 patients with apnea-hypopnea indices of 5 or more were analyzed. Baseline values for the urinary albumin-creatinine ratio (UACR), serum levels for three markers of AKI (cystatin C, neutrophil gelatinaseassociated lipocalin [NGAL], interleukin-18 [IL-18]), and polysomnography data were recorded and analyzed. Patients then were followed for 6 months of continuous positive airway pressure (CPAP) treatment. Results: At baseline, UACRs were greater in patients with more severe OSA (P = .005, r = .329). All three serum markers of AKI (cystatin C, NGAL, and IL-18) studied were positively correlated with OSA severity, and two (cystatin C and IL-18) were positively correlated with the frequency of oxygen desaturation during sleep. However, none of the AKI markers had positive correlations with UACR. After 6 months of CPAP treatment, UACR and IL-18 were decreased significantly in patients with good adherence. Conclusions: Albuminuria and levels of three serum markers of AKI (cystatin C, NGAL, IL-18) were positively correlated with OSA severity, and good adherence with CPAP treatment decreased albuminuria and interleukin-18 levels. These results may provide additional tools for assessing early renal injury in patients with OSA.

MicroRNA-421 protects against chronic intermittent hypoxia-induced vascular endothelial cell injury by targeting TLR4

“…It is well accepted that OSAS is chronic respiratory disease that can induce CIH, which may result in endothelial dysfunction and multiple organ damage [3,4,6]. Many miRNAs, such as miR-664a-3p, miR-630, and miR-30a, play important roles during the development of OSAS [6,13,14].…”

“…It may be caused by obesity, advanced age, male gender, alcohol abuse, and nasal obstruction [2]. It is well-known that OSAS can cause damage to multiple organs and systems, including the cardiovascular system, nervous system, lung, and kidney, [3][4][5]. Importantly, chronic intermittent hypoxia (CIH) is a characteristic of OSAS [4] and a key factor of oxidative stress that induce the release of reactive oxygen species (ROS), which subsequently results in systemic inflammation [1].…”

Author Response

“…We thank Voulgaris et al for their interest in our study. 1 We agree the relationship between obstructive sleep apnea (OSA) and chronic kidney disease (CKD) has been more elucidated over the past years. [2][3][4] We also agree that nocturnal hypoxia, such as intermittent hypoxia in OSA, may contribute to the kidney injury.…”

Sleep Apnea and the Kidney

“…CPAP therapy is associated with a reduction in common risk factors for CKD, which could warrant an improvement in kidney function. CPAP prevents nocturnal oxygen desaturations, slightly decreases blood pressure [69], and reduces renal RAS activity [70] and circulating inflammatory markers including IL-18, a marker of acute kidney injury [71].…”