Tonsillectomy and IgA nephritis.

IgA nephritis (IgAN) is an autoimmune disease characterized by deposits of IgA in the glomerular mesangium. Clinically, the disease may be punctuated by episodes of macroscopic haematuria often associated with pharingotonsillitis or may be oligosyntomatic with microscopic haematuria and mild proteinuria. The natural course of IgAN may be indolent and benign; however, some 30-50% of patients may progress to end-stage renal disease when follow-up is extended to ≥20 years. In patients with IgAN, circulating IgA1 molecules have an aberrant structure of O-glycans in the hinge region, which is characterized by abbreviated glycans composed of N-acetylgalactosamine, with or without sialic acid. These aberrant IgA1 trigger the production of autoantibodies, with formation of immune complexes that deposit in the mesangium causing inflammation and production of extracellular matrix. A number of experimental and clinical data outlined a possible pathogenetic role of tonsillitis. As a consequence, tonsillectomy has been frequently performed in Japan. Observational studies, made in patients with normal renal function and mild proteinuria, reported that tonsillectomy could reduce the episodes of macrohaematuria as well as the entity of microhaematuria and proteinuria. However, the available studies had short-term follow-up and could not asses the role of tonsillectomy in protecting from renal function deterioration. In a longitudinal retrospective study, Isseki et al. compared the outcome of tonsillectomized patients with IgAN with that of IgAN patients who did not receive tonsillectomy. Tonsillectomized patients had a higher number of remissions and a better slope of glomerular filtration rate in comparison with controls. These data are interesting and suggest that tonsillectomy may prevent renal dysfunction in patients with IgAN and normal renal function. However, the retrospective nature of the study and the presence of some confounding factors require further investigations to confirm these promising data.