Spot urinary sodium for assessing dietary sodium restriction in cirrhotic ascites

To evaluate the accuracy of spot urinary Na/K and Na/creatinine (Cr) ratios as an alternative to 24-h urinary sodium in monitoring dietary compliance in patients with liver cirrhosis and ascites treated with diuretics. The study was carried on 40 patients with liver cirrhosis and ascites treated with diuretic therapy. Patients were divided into two groups according to 24-h urinary sodium. We measured spot urine Na/K ratio, Na/Cr ratio and 24-h urinary sodium. Student's t test was used to compare the interval variables and chi(2) test to compare the nominal variables between the two groups. Receiver operator characteristic curve was used to identify the best cutoff point for Na/K and Na/Cr ratio. The best cutoff point for Na/K ratio was 2.5 (P < 0.001) and area under the curve (AUC) was 0.9, and for Na/Cr ratio, the best cutoff point was 35 (P < 0.001) and AUC was 0.885. Na/K ratio showed higher sensitivity and accuracy compared to Na/Cr ratio (87.5% and 87% for Na/K ratio; 81% and 85% for Na/Cr ratio, respectively). Spot urine Na/K ratio has adequate accuracy for assessment of dietary sodium restriction compared with 24-h urinary sodium in patients with liver cirrhosis and ascites.