Protein C, protein S and antithrombin III in children with portal vein obstruction

Portal vein obstruction is the most common single cause of portal hypertension in children and its cause is unknown in most instances. The aim of the present study was to evaluate the incidence of protein C, protein S and antithrombin III deficiencies and to screen for possible genetic deficiencies of these proteins.

A prospective study was undertaken in 20 consecutive children with portal vein obstruction, their parents and 20 matched healthy children.

Children with portal vein obstruction displayed a reduction in protein C (p<0.05), protein S (p<0.0001), and antithrombin III (p<0.001) activities as compared with controls. Protein C and protein S activities were below 60% in nine and eleven of the children with portal vein obstruction, respectively, and antithrombin III activities were below or equal to 85% in ten of them. Repeated assay of protein C activity in seven children following a surgical portosystemic shunt showed a decrease as compared with preoperative values. Protein C, protein S and antithrombin III were normal in all parents, except two mothers in whom the levels of protein S activity and protein S antigen were found to be either below or at the lower limit of the normal range.

These results indicate that protein C, protein S and/or antithrombin III deficiencies are frequently found in children with portal vein obstruction but are not likely to be of genetic origin in most cases.