Functional protein C and anti-cardiolipin antibody in children with portal vein thrombosis

Abstract

Background: Portal vein thrombosis (PVT) is a common cause of portal hypertension in children from developing countries. Deficiencies of proteins C and S and elevated anticardiolipin antibody (aCL) levels have been shown to predispose to venous thrombosis. We studied these factors in children with idiopathic PVT. Methods: 19 children with PVT (mean [SD] age 5.7 [2.1] y; 15 boys) were studied; all had variceal bleeding, and had PVT on ultrasonography. Functional protein C activity was measured using a clotting assay; if it was normal, a clotting assay for functional protein S activity was performed. IgG aCL levels were measured in all sera using an in-house standardized solid-phase ELISA. Results: Protein C functional activity ranged from 4% to 109%. Eight children had activity below 70%, the lower cut-off of the normal range. Protein S assay, done in 10 of the 11 children with normal protein C activity levels, was normal (above the cut-off level of 65% of the normal range). IgG aCL levels were abnormally elevated (>mean + 2SD of 16 healthy control children) in nine children; of these, three had associated protein C deficiency. Thus, of the 19 children with idiopathic PVT, 14 had abnormality in one or more tests. Conclusion: A majority of children with PVT of unknown etiology have functional protein C deficiency or abnormally elevated levels of aCL antibodies.