A 24-year-old man develops rapidly progressive glomerulonephritis with hemoptysis over one week. Renal biopsy immunofluorescence shows smooth linear staining of glomerular basement membranes for IgG. Which additional test will most likely be positive?
- A Antineutrophil cytoplasmic antibody against proteinase 3
- B Antibody directed against the noncollagenous domain of the alpha-3 chain of type IV collagen ✓
- C Granular staining for C3 along capillary walls
- D Serum cryoglobulins of mixed IgG-IgM type
Correct answer: B. Antibody directed against the noncollagenous domain of the alpha-3 chain of type IV collagen
Explanation
Linear IgG staining of the GBM defines anti-GBM antibody disease, which with pulmonary hemorrhage is Goodpasture syndrome. The antigen is the NC1 domain of the alpha-3 chain of type IV collagen. PR3-ANCA suggests granulomatosis with polyangiitis, which shows pauci-immune crescents without linear staining, and granular C3 indicates an immune complex process.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.