Subentities within adult primary IgA-nephropathy.

Since its definition is purely descriptive, IgA-nephropathy (IGAN) may comprise more disease entities which share the (epi)phenomenon of mesangial IgA-depositions. IGAN patients with macroscopical hematuria (macro-H) differ from the other IGAN patients in 9 aspects: history, HLA-DR, Gm-allotypes, actuarial kidney survival, initial creatinine clearance, initial proteinuria, initial microhematuria, age at presentation and light microscopy of the renal biopsy. The difference in the last five parameters may either be explained by the existence of subentities or by earlier detection of patients with macro-H. The dissimilarity in the first four parameters can only be due to the former theory. Therefore, we conclude that IGAN probably comprises at least two disease entities.