Value of Serum Ascitic Albumin Gradient in Differential Diagnosis of Ascitic Etiologies

Background: Serum;ascitic albumin gradient (SAAG) is an indirect parameter reflecting the portal vein pressure. Aims: To evaluate the diagnostic value and reliability of SAAG and other laboratory tests in patients with ascites. Methods: Case records of 122 patients with ascites were reviewed retrospectively. The patients were divided into 2 groups, the group associated with portal hypertension (68 patients) and the group without portal hypertension (54 patients). The SAAG were calculated using the serum and ascitic albumin levels on the same day. Results: The mean level and standard deviation of SAAG of the group associated with portal hypertension and the group without portal hypertension was 18.5 g/L±5.3 g/L, and 7.0 g/L±3.1 g/L, respectively (P0.001). Using SAAG≥11 g/L as the cut;off value, the diagnostic sensitivity for ascites associated with portal hypertension was 95.6%, diagnostic specificity was 98.1%, diagnostic accuracy 96.7%, positive predictive value 98.5%, negative predictive value 94.6%. Conclusions: Although the SAAG cannot make a diagnosis of the etiologies of ascites, it is useful for directing further evaluation. High SAAG is related to high portal venous pressure. If tuberculous peritonitis and autoimmune disease can be eliminated, the patients with low SAAG suggest the presence of probable malignant tumor requiring further investigation.