Differential Diagnosis of Human Ascites: Inhibitors of the Contact System and Total Proteins

Abstract

Buø L, Karlsrud TS, Dyrhaug G, Jacobsen MB, Bell H, Johansen HT, Aasen AO. Differential diagnosis of human ascites: inhibitors of the contact system and total proteins. Scand J Gastroenterol 1993;28:777-782.

To assess their accuracies as markers for malignancy, we assayed α₂-macroglobulin, C1-inhibitor, α₁,-protease inhibitor, and total proteins in ascites and plasma from patients with gastrointestinal cancer (n = 15) and non-malignant liver disease (n = 13), using functional and immunologic assays. For all inhibitors and total proteins determined in ascites, the values in the cancer group were significantly higher than the corresponding values in the group with non-malignant liver disease. The diagnostic accuracy for differentiating malignancy-related from non-malignant ascites was 93% for a _α1-protease inhibitor value ≥ 50% of the pool plasma value and 90% for _α2-macroglobulin ≥ 16%, C1-inhibitor ≥ 40% (all functional assays), and total proteins ≥ 20g/l (biuret). In conclusion, functional assays for oymacroglobulin, C1-inhibitor, and α₂,-protease inhibitor and determination of total proteins in ascites appeared to be very informative tests for the differential diagnosis of ascites. The test for α₁-protease inhibitor gave higher specificity (92% versus 77%) and likelihood ratio for a positive test (12 versus 4) compared with the other tests.

Key Words:

• Ascites differential diagnosis
• liver failure
• malignancy
• protease inhibitors
• total proteins