A study of serum uric acid and lactate level in patients with obstructive sleep apnea syndrome

Background Tissue hypoxia due to repeated sleep apneas leads to evolution of reactive oxygen stress and serum levels of uric acid (UA) and lactate in patients with obstructive sleep apnea syndrome (OSAS). Objective The objective of this study was to determine whether there is an association between OSAS and both serum UA and lactate levels as potential markers of tissue hypoxia and their relation with OSAS severity. Participants and methods Thirty participants were classified into two groups. Group I included 10 control persons matched to obstructive sleep apnea (OSA) patients by sex, age, and BMI. Group II included 20 patients with OSA as diagnosed by polysomnography [apnea–hypopnea index (AHI)≥5]. The following were conducted: full history, clinical examination, complete overnight polysomnography to detect AHI, oxygen saturation parameters, and snoring index. Finally serum lactate and UA levels were assessed through two samples of peripheral arterial blood: one before sleep and the second at the end of polysomnography. Results In OSA patients, the mean levels of serum UA and lactate both before and after sleep were significantly higher compared with controls with significant overnight increase after sleep and high percent of change of serum UA and lactate levels. These higher levels were independent of age, sex, and BMI. Moreover, UA and lactate levels after sleep in OSA patients were significantly correlated with OSA severity (AHI) and degree of nocturnal hypoxia through positive correlation with (%TST Conclusion Both serum UA and lactate may be considered as potential markers of tissue hypoxia and related to OSAS severity. Their levels were significantly elevated after sleep with significant overnight rise and significant positive correlation with AHI, %TST