Early IgA nephropathy: paradigm evolving from a clinical concept into a histological measure

Abstract

The designation of “early” IgA nephropathy is often used in patients with normal renal function, no or mild proteinuria, and absence of other features, but the term is in fact poorly defined judging from the varying norms adopted. Even with stringent clinical criteria used to characterize clinical early IgA nephropathy, these may not be correlated with the prediction of disease outcome, nor with the severity of renal lesions. Due to such limitations, the clinical reference to early IgA nephropathy represents more a concept than an accurate measure. The histological definition of “early” IgA nephropathy appears to be different as the grading of biopsy permits one to segregate by semiquantitation patients with early renal lesion and very low risk of progression. This review puts the emphasis on the morphologic definition of early IgA nephropathy based on objective criteria, and on its practical consequences. The clinical implications include a better patient selection in therapy, and the potential to enhance results of treatment as well as for the appraisal of clinical trials. We also suggest that all patients suspected for IgA nephropathy, including those in early clinical stage should undergo renal biopsy because the information yielded are critical to the management and therapy.