Correlation of serum sodium,serum potassium concentrations and their ratios with blood pressure in older patients

Background Several studies have investigated the relationship between dietary or urine potassium and sodium and blood pressure, but few have evaluated the relationship between serum potassium or sodium and blood pressure. Therefore, we evaluated the association between serum potassium and sodium and blood pressure in an older Chinese population. Methods A total of 241 older patients admitted to Hebei General Hospital were consecutively enrolled. 150 patients were divided into hypertension group and 91 patients were divided into normal blood pressure group. Correlation analysis and multiple logistic regression were used to analyze the relationship between serum sodium, serum potassium and their ratio with blood pressure. Receiver operating characteristic (ROC) curve was used to analyze the predictive value of serum sodium/potassium ratio for hypertension in this population. Results Serum potassium was negatively correlated with systolic blood pressure (r=-0.341, P < 0.001), serum sodium-to-potassium ratio was positively correlated with systolic blood pressure (r = 0.349, P < 0.001), and serum sodium was not significantly correlated with systolic blood pressure (r = 0.105, P < 0.001). Serum sodium/potassium concentration ratio (OR = 1.094, 95%CI 1.003–1.193, P = 0.043) was still an independent influencing factor of hypertension. The area under ROC curve of serum sodium-to-potassium ratio for predicting hypertension in older patients was 0.666 (95%CI 0.599–0.733, P < 0.001). Conclusions Serum potassium level is related to blood pressure in the older population, and serum sodium-to-potassium ratio is related to hypertension in the older patients, which is an independent risk factor for hypertension in this population.