Hyponatremia in cirrhosis: Risk factors and prognostic value

Background Hyponatremia is the most common electrolyte abnormality encountered in cirrhotic patients. Recent studies have shown that hyponatremia was correlated with severity of cirrhosis and associated with increased risk of complications and mortality. However this relationship is still unclear. The aims of the present study were to search predictive factors for hyponatremia in cirrhosis and to assess its prognostic value. Methods We performed a retrospective study, including consecutive cirrhotic patients admitted to our department between January 2011 and April 2014. Patients and cirrhosis characteristics were studied. Serum sodium levels were determined at admission. The cutoff level of 130 mmol/l was chosen because it is widely accepted to define hyponatremia in patients with cirrhosis. Predictive factors of hyponatremia development and its impact on the outcome (cirrhosis complications and survival) were evaluated. Results We included 143 cirrhotic patients: 67 females (46.9%) and 76 males (53.1%) with a mean age of 58 years. Etiology of cirrhosis was mainly viral (56.7%). Child-Pugh stage was B in 41.2% and C in 25.9%. Mean MELD score was 15 [6-40]. The prevalence of dilutional hyponatremia as defined by a serum sodium concentration ≤130 mmol/L or ≤135 mmol/L was 10.5% and 31.4% respectively. Serum sodium level ≤130 mmol/L was strongly associated with severity of liver function impairment as indicated by Child-Pugh C (OR=7.84;p<0.001), and MELD score> 16 (OR=6.76; p=0.001). Survival without complications was reduced in patients with hyponatremia but was only significant if a serum sodium concentration ≤135 mmol/L was considered (p=0.012). Survival without hepatic encephalopathy and without hepatorenal syndrome was significantly reduced in patients with hyponatremia (p<0.001 for both). Global survival was also reduced in patients with hyponatremia at 1 year: 22.5% versus 68.7%, as well as mean global survival: 8.3 versus 32.8 months (p<0.0001). Conclusion Low serum sodium level was correlated with severity of cirrhosis.  Hyponatremia was a negative prognostic factor associated with increased short-term morbi-mortality.