Clinical relevance of hyponatraemia for the hospital outcome of cirrhotic patients

BACKGROUND: Hyponatraemia frequently develops in cirrhotic patients whose ability to excrete free water is impaired. The role of hyponatraemia in the prognosis of such patients is unclear. AIM: To evaluate prevalence, clinical associations and prognostic impact of hyponatraemia in cirrhotic inpatients. PATIENTS: A series of 156 cirrhotic patients consecutively admitted to our department, for a total of 191 admissions, were studied. METHODS: Serum sodium levels were determined at admission and repeated at least weekly in all patients. The clinical status and the survival of patients with hyponatraemia (< or = 130 mmol/l) were compared to those of patients with normal sodium levels. RESULTS: Hyponatraemia was found in 57 out of 191 admissions (29.8%). Bacterial infections, ascites, chronic diuretic therapy, but not gastrointestinal bleeding or renal failure, were more frequent in patients with hyponatraemia than in those with normal sodium levels. In 3 cases, none of these conditions were present and hyponatraemia was defined as "spontaneous". Hospital death rate was increased in patients with hyponatraemia (26.3% versus 8. 9%, chi2=8. 55, p=0.003). By multivariate analysis, the only parameters independently associated with survival were high serum bilirubin (p=0.006) and high serum urea levels (p=0.019). Twenty-five patients developed severe hyponatraemia (<125 mmol/l) during hospital stay. This event was associated with a concomitant bacterial infection in 21 cases. The mortality rate of these patients was very high (48%). CONCLUSIONS: Hyponatraemia is frequent in cirrhotic inpatients. It is seldom a spontaneous event but rather occurs in association with ascites, chronic use of diuretics or bacterial infections. It is a negative prognostic factor associated with increased short-term mortality.