Low sodium to potassium ratio in spot urine sample is associated with progression to acute kidney injury and mortality in hospitalized patients with cirrhosis

Abstract

Backgroundsodium 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. Aimsto 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. Methodsprospective cohort study included 225 adult subjects. Urine samples were obtained within 48 h of hospitalization. ResultsAKI 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. Conclusionslow Na/Kur ratio in spot urine sample is associated with progression to AKI and lower short-term survival in patients hospitalized for decompensated cirrhosis.