After 8 hours of hemofilttration: Na+ và K+ (mmol / L) in the elderly group versus the young group were 139.03 ± 4.25 vs 141.08 ± 7.33 (p > 0.05) and 3.87 ± 0.69 vs 3.90 ± 0.53 (p > 0.05) respectively.