RESUMEN
BACKGROUND: sodium to potassium ratio in spot urine sample (Na/Kur) is a surrogate marker of sodium excretion that is recommended for the management of patients with ascites due to cirrhosis. AIMS: to investigate Na/Kur ratio and fractional excretion of sodium (FENa) in patients admitted with decompensated cirrhosis, evaluating its relationship with acute kidney injury (AKI) and prognosis. METHODS: prospective cohort study included 225 adult subjects. Urine samples were obtained within 48 h of hospitalization. RESULTS: AKI at admission was observed in 32.9% of patients and was associated with lower Na/Kur ratio, but not FENa. Among 151 subjects initially without kidney dysfunction, AKI at some point during hospitalization occurred in 26.2% and was independently associated with low Na/Kur ratio at admission. AKI was observed in 44% of the patients with Na/Kur ratio < 1 and only in 8% when values ≥ 2. Na/Kur ratio at admission was independently associated with 30-day mortality, with Kaplan-Meier survival probability of 78.8% for Na/Kur ratio < 1 and 93.6% for values ≥ 1. CONCLUSIONS: low Na/Kur ratio in spot urine sample is associated with progression to AKI and lower short-term survival in patients hospitalized for decompensated cirrhosis.