IgA nephropathy (IgAN) is common in medical kidney biopsy. The diagnosis of IgAN is usually straightforward with predominant glomerular mesangial staining with IgA along with clinical hematuria/acute nephritis. Problems arise when patients might have other causes for glomerular IgA deposition.
Cassol et al. investigated whether immunostaining for galactose-deficient IgA1 (GD-IgA1 or KM-55) can be used to differentiate between primary IgAN and others including secondary IgAN, infectious (staphylococcus)-related GN and incidental IgA deposition. They found GD-IgA1in all patients with IgAN and most patients in other category. Therefore GD-IgA1 immunostaining cannot reliably differentiate primary IgAN from other causes of dominant IgA glomerular deposition.
https://doi.org/10.1093/ndt/gfz152
