Relationship between aldosterone and the metabolic syndrome in patients with obstructive sleep apnea: Effect of continuous positive airway pressure treatment

Background: Metabolic syndrome (MS) occurs frequently in patients with obstructive sleep apnea (OSA). We hypothesized that aldosterone levels are elevated in OSA and associated with the presence of MS. Methods: We studied 66 patients with OSA (33 with MS and 33 without MS) and 35 controls. The occurrence of the MS was analyzed according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) clinical criteria. Measurements of plasma renin activity (PRA), aldosterone, aldosterone:PRA ratio, creatinine, glucose, triglycerides, cholesterol and HDL cholesterol were obtained at baseline and after CPAP treatment. Results: Aldosterone levels were associated to severity of OSA and higher than controls (p= 0.046). Significant differences in aldosterone levels were detected between OSA patients with and without MS (p= 0.041). A significant reduction was observed in the levels of aldosterone in patients under CPAP treatment (p=0.012). Conclusion: This study shows that aldosterone levels are elevated in OSA in comparison to controls, and that CPAP therapy reduces aldosterone levels. It also suggests that aldosterone excess may predispose or aggravate the development of metabolic syndrome in patients with OSA and could be an additional risk factor in the metabolic and cardiovascular complications of OSA patients.