Characteristics of immunoglobulin A nephropathy with mesangial immunoglobulin G and immunoglobulin M deposition

Aim: There are immunoglobulin (Ig)A nephropathy (IgAN) cases showing mesangial IgG and/or IgM deposition, however, their characteristics have remained unknown. Methods: Three hundred and eighty‐four IgAN patients were divided according to the existence of mesangial IgG and/or IgM deposition: IgA deposition only (A group, n = 77); IgA and IgM deposition (AM group, n = 114); IgA and IgG deposition (AG group, n = 36); and IgA, IgG and IgM deposition (AGM group, n = 157). Clinical and histological findings, and outcomes were examined and compared among these four groups. Results: At the time of renal biopsy, serum creatinine was significantly higher in the A and AM group, however, creatinine clearance did not differ among the four groups. The ratio of glomerular obsolescence was significantly higher in the AM group than in the A and AGM group, and the ratio of glomerular tuft adhesion was significantly higher in the AM, AG and AGM group than in the A group. However, the other clinical and histological findings, electron microscopic findings and renal survivals did not differ among the four groups. Proteinuria was independently associated with an increase in risk of doubling of creatinine (P = 0.005), however, IgG and IgM depositions were not by multivariate Cox regression. Conclusion: The presence of other Ig classes, besides IgA deposits, was found to be associated with glomerular obsolescence and tuft adhesions, however, without any effect on renal survival in IgAN.