Mild hyponatremia has a substantial influence on clinical outcome of patients on the waiting list and after liver transplantation.

Introduction Waiting list mortality is high in patients awaiting liver transplantation (LT). Despite the use of the Model for Endstage Liver Disease (MELD) score, patients with severe hyponatremia have an even worse waiting list survival. We assessed the impact of mild hyponatremia on LT waiting list survival and overall survival. We also aim to identify if there are any patient groups that are underserved in the MELD based allocation system. Methodology Data were collected from 3 transplant centers located in The Netherlands, Germany, and the United States of America. Serum bilirubin, creatinine, sodium, and international normalized ratio (INR) were collected and MELD scores calculated using the standard formula. Mild hyponatremia was defined as serum sodium level of 130-134 mmol/L. Results In total 1658 patients were included in this study. A strong correlation was found between serum sodium and overall and waiting list survival (P < 0.001). Post-LT survival was also significantly decreased in the mild hyponatremia group (P < 0.001). Waiting list survival for patients with serum sodium levels 130-134 mmol/L was worse compared to patients with normal sodium levels in all three centers together and each center individually (P < 0.001). Waiting list and overall survival was significantly worse in the 166 patients with cholestatic liver disease compared to patients with non-cholestatic liver disease (P = 0.041; P = 0.005). Post-LT survival also was significantly worse in this group (P = 0.022). Conclusion Mild hyponatremia is associated with significantly worse waiting list survival in patients awaiting LT. It is also associated with increased post-LT mortality. Patients listed for cholestatic liver disease may be underserved in the current allocation model. Serum sodium should therefore have a more prominent role in liver allocation. [ABSTRACT FROM AUTHOR]