Prevalence of hyponatremia and associated factors in patients with chronic kidney disease: the Fukuoka Kidney Disease Registry (FKR) study

Background Hyponatremia is a common and important electrolyte disorder. However, the prevalence and factors associated with hyponatremia in patients with chronic kidney disease (CKD) are unknown. Methods We studied the factors associated with hyponatremia (< 135 mEq/L) in CKD patients registered in the Fukuoka Kidney Disease Registry (FKR) study using a logistic regression model variable selected using the variable reduction method. Results We analyzed the baseline characteristics of 4367 participants with CKD (age, 64 ± 16 years; male, 56.1%). Hyponatremia was detected in 2.0% of the patients at baseline, and multivariate logistic analysis showed that the independent factors for hyponatremia were body mass index (odds ratio [OR] 0.91; 95% confidence interval [CI] 0.85–0.97), prescription of benzodiazepine (OR 2.31; 95% CI 1.39–3.86), blood hemoglobin level (OR 0.76; 95% CI 0.65–0.88), and serum C-reactive protein level (OR 1.27; 95% CI 1.04–1.54). Conclusion The cross-sectional analysis using baseline data from the FKR study revealed independent factors associated with hyponatremia in patients with decreased kidney function. Longitudinal analyses of the FKR cohort are needed to evaluate the effects of these factors on the prognosis of hyponatremia in patients with CKD.