A Case of Membranoproliferative Glomerulonephritis with False-Positive Reaction for Anti-GBM Antibody / 대한신장학회지

ABSTRACT

Anti-glomerular basement membrane (Anti-GBM) nephritis is an autoimmune disorder characterized by rapidly progressive crescentic glomerulonephritis (RPGN). The treatment of anti-GBM nephritis with plasmapheresis, steroids and immunosuppressant has improved outcomes. An early diagnosis is essential for the survival of patients and a recovery of renal function. The diagnosis of anti-GBM disease has been traditionally based on the demonstration of linear deposits of immunoglobulins along the glomerular basement membrane by immunofluorescence (IF) microscopy. However, a kidney biopsy cannot always be easily performed in such ill patients. Recent development of specific enzyme immunoassays for anti-GBM antibody in the serum has made possible a provisional diagnosis without a kidney biopsy. A 46-year-old male patient with hypertension and hepatitis B presented with generalized edema and general weakness. Laboratory findings were compatible with acute renal failure and nephrotic syndrome with positive serum anti-GBM antibodies. After plasmapheresis with steroid pulse therapy, renal biopsy was performed and diagnosed as membranoproliferative glomerulonephritis (MPGN) with granular deposit of Ig G and C3. Follow-up antibody titers were negative. This case demonstrates the possibility of false-positive anti-GBM antibody in the serum. Therefore, enzyme immunoassay for anti-GBM antibody should be used only as a screening or follow-up test in patients that have been confirmed positive by IF microscopy.