Clinical Information

Anti-glomerular basement (GBM) disease is a rare autoimmune disease, with an estimated incidence of 0.6-1.79 cases per million population per year.(1) Without prompt treatment, this disease is potentially fatal. Patients may present with rapidly progressive glomerulonephritis, pulmonary hemorrhage, or both.(2,3) The serological hallmark of this disease is the presence of anti-GBM antibodies of the IgG isotype. Anti-GBM antibodies bind to the non-collagenous domain 1 (NC1) of the alpha3 chain of type IV collagen, which is one of the main components of the kidney and lung basement membranes. Deposition of anti-GBM antibodies in the kidney and lungs triggers complement activation and production of reactive oxygen species, ultimately leading to vascular necrosis and damage to the GBM.

The diagnosis of anti-GBM disease in a patient with compatible clinical symptoms is often confirmed by detecting the presence of anti-GBM antibodies. This can be accomplished by a variety of antigen-specific, solid-phase immunoassays. Given the implications of this testing, understanding the diagnostic sensitivity and specificity of anti-GBM antibody methods is critical. In a recent meta-analysis, a pooled sensitivity of 93% (95%CI: 84-97%) and a pooled specificity of 97% (95%CI: 94-99%) was demonstrated across 11 methods.(4) In addition, some studies have suggested a prognostic role for anti-GBM antibodies, with higher titers being associated with increased mortality. However, it appears that this effect can largely be abrogated by prompt and aggressive treatment, particularly plasmapheresis.(1)