What is the role of anti–GBM antibody testing in the workup of Goodpasture syndrome (anti–glomerular basement membrane disease) (anti-GBM)?

Updated: Dec 16, 2020
  • Author: Pranay Kathuria, MD, FACP, FASN, FNKF; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Serologic assays for anti-GBM antibodies are valuable for confirming the diagnosis and monitoring the adequacy of therapy. Radioimmunoassays or enzyme-linked immunosorbent assays (ELISAs) for anti-GBM antibodies are highly sensitive (>95%) and specific (>97%) but are performed in only a few laboratories. Positive results should be confirmed by Western blotting on collagenase-solubilized human GBM, especially if a kidney biopsy is not being performed.

In a comparison study of 4 immunoassay-based anti-GBM antibody kits, all the assays showed comparably good sensitivity (94.7-100.0%), whereas specificity varied considerably (90.9-100.0%). The recombinant antigen fluorescence immunoassay demonstrated the best sensitivity/specificity. [23]

Healthy individuals may have circulating antibodies against GBM belonging to IgG2 and IgG4 subclasses. With onset of clinical disease, IgG1 and IgG3 subclasses increase and levels may correlate with disease severity. [7]

A study by Yang et al indicated that higher levels of circulating anti-GBM antibodies against the epitopes EA and EB occurred in patients whose renal disease was more severe and that these patients had a worse prognosis. Correlation was noted between the levels of anti-GBM antibodies and the serum creatinine at diagnosis and the presence of oliguria. Correlation existed between the percentage of crescents on biopsy and levels of antibodies, but it was significant only for anti-EA antibodies (P < .05). [24]

Cases of anti-GBM antibody–negative anti-GBM disease have been reported. Kidney biopsy is required to diagnose this atypical presentation. [25, 26]  

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