Are ascitic electrolytes usable in cirrhotic patients? Correlation of sodium, potassium, chloride, urea, and creatinine concentrations in ascitic fluid and blood.

BACKGROUND: Treatment of ascitic cirrhosis requires monitoring of blood biochemistry. A direct measure of ascites could simplify the medical procedure. We aimed to assess the correlation of sodium (Na), potassium (K), chloride (Cl), urea (U), and creatinine (Creat) in ascitic fluid and venous blood.
METHODS: Ascitic fluid and venous blood samples were collected simultaneously from 70 cirrhotic patients. Na, K, Cl, U, and Creat were measured in all samples using a biochemical auto-analyzer.
RESULTS: Results are expressed as the mean and SD of 200 concomitant samples of ascitic fluid and venous blood (mmol/L for Na, K, and Cl; g/L for U; mg/L for Creat). In ascites and blood the results were, respectively: 133.1+/-6.6 and 131.8+/-6.3 for Na (p<0.0001, r=0.95), 4.1+/-0.8 and 4.3+/-0.9 for K (p<0.0001, r=0.90), 107.2+/-7.6 and 101+/-7 for Cl (p<0.0001, r=0.93), 0.54+/-0.52 and 0.53+/-0.5 for U (p<0.0001, r=0.99), and 9.8+/-7.5 and 11+/-7 for Creat (p<0.0001, r=0.99). Analysis of ascites predicted blood results for different cut-offs (Na< or =125, K< or =3.2, K> or =5.5 and Creat> or =14) with a sensitivity of 1.00, 0.89, 0.71, and 0.92, and a specificity of 1.00, 0.95, 0.98, and 0.92, respectively.
CONCLUSIONS: Correlations for Na, K, Cl, U, and Creat are strong between ascites and venous blood in cirrhotic patients. These parameters could, therefore, be assayed directly in ascitic fluid to monitor diuretic therapy in patients without venous access or when biochemical measurements, such as liver tests or coagulation tests, are not required, and in patients with poor venous access.