Hyponatremia and lower normal serum sodium levels are associated with an increased risk of all-cause death in heart failure patients.

A total of 3649 patients were included, and the mean sodium level was 137.19 ± 4.36 mmol/L, with a range from 115.6 to 160.9 mmol/L. During a median follow-up of 1101 days, mortality occurred in 1413 (38.7%) hospital survivors. After adjustment for age, sex, and other potential confounders, patients with sodium levels <135 mmol/L (hazard ratio [HR]: 1.67; 95% confidence interval [CI]: 1.29-2.16) and 135-137 mmol/L (HR: 1.34; 95% CI: 1.01-1.78) had an increased risk of all-cause mortality compared to those with sodium levels of 139-141 mmol/L.