Membranoproliferative glomerulonephritis induced by portosystemic shunt surgery for non-cirrhotic portal hypertension.

The liver and spleen both have important phagocytic functions and contain monocytes/macrophages which clear immune complexes. We describe here three patients who presented proteinuria and hematuria 7 to 13 years after portosystemic shunt surgery, which diverted portal venous blood to the systemic circulation. They had hematemesis and/or melena and underwent mesocaval shunt surgery and splenectomy in childhood because of non-cirrhotic portal hypertension with esophageal varices. Renal biopsy specimens revealed findings characteristic of membranoproliferative glomerulonephritis (MPGN) type I. Immunohistologically, these three cases were accompanied by a distinct IgA deposition along with a marked C3 deposition. The IgA observed in these three cases contained not only IgA1 but also IgA2, which is the predominant form of mucosal IgA. On the other hand, of 20 patients with idiopathic MPGN type I with IgA deposition (n = 20), only two were positive for IgA2, and the distribution was focal and segmental. Our study shows that MPGN type I may have developed secondary to portosystemic shunt. This secondary form of MPGN type I may be caused by a reduced clearance of immune complexes in the liver and their deposition in the glomerulus, since a portosystemic shunt routes portal venous blood from the intestinal tract directly to the systemic circulation.