DIFFERENTIAL-DIAGNOSIS OF HUMAN ASCITES - INHIBITORS OF THE CONTACT SYSTEM AND TOTAL PROTEINS

To assess their accuracies as markers for malignancy, we assayed alpha 2-macroglobulin, Cl-inhibitor, alpha1-protease inhibitor, and total pr oteins in ascites and plasma from patients with gastrointestinal cance r (n = 15) and non-malignant liver disease (n = 13), using functional and immunologic assays. For all inhibitors and total proteins determin ed in ascites, the values in the cancer group were significantly highe r than the corresponding values in the group with non-malignant liver disease. The diagnostic accuracy for differentiating malignancy-relate d from non-malignant ascites was 93% for a alpha1-protease inhibitor v alue greater-than-or-equal-to 50% of the pool plasma value and 90% for alpha2-macroglobulin greater-than-or-equal-to 16%, Cl-inhibitor great er-than-or-equal-to 40% (all functional assays), and total proteins gr eater-than-or-equal-to 20 g/l (biuret). In conclusion, functional assa ys for alpha2-macroglobulin, Cl-inhibitor, and alpha1-protease inhibit or and determination of total proteins in ascites appeared to be very informative tests for the differential diagnosis of ascites. The test for alpha1-protease inhibitor gave higher specificity (92% versus 77%) and likelihood ratio for a positive test (12 versus 4) compared with the other tests.