ANCA-GBM dot-blot test in diagnosis of patients with glomerulonephritis

Patients with rapidly progressive glomerulonephritis who are positive for anti-neutrophil cytoplasmic antibody (ANCA) or anti-glomerular basement membrane (GBM) antibodies may develop chronic renal failure leading to end-stage renal disease (ESRD) within days or weeks. The early serologic detection of auto-antibodies associated with ANCA and anti-GBM diseases will be helpful in preventing ESRD. We evaluated the combined ANCA-GBM dot-blot strip assay (Biomedical Diagnostics, Brugge, Belgium) in 30 consecutive patients with biopsy proven glomerulonephritis (GN). MPO- and PR3-ANCA were detected in 5 and 2 samples, respectively. Three samples were positive for both MPO- and PR3-ANCA (all 3 had focal segmental necrotizing GN). One patient was diagnosed as having Goodpastures' syndrome (the only anti-GBM positive result) and two had Wegener's granulomatosis (the two PR3-ANCA positive results). Two additional samples were equivocal: positive for MPO-ANCA and PR3-ANCA, respectively. Patients positive only for MPO-ANCA had only limited extrarenal organ manifestations. Anti-PR3 positive patients with necrotizing glomerulonephritis had a more dramatic deterioration of their renal function at diagnosis. Radiographically, these patients had nodular or pneumonia-like lesions. Acute respiratory failure necessitating mechanical ventilation was developed in one GBM positive patient. In conclusion, the ANCA-GBM dot-blot is a useful screening tool in situations where conventional ANCA testing is not readily available.