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Abstract: SA-PO662

The Characteristics of IgM Nephropathy Compared to Other Glomerular Diseases

Session Information

Category: Glomerular Diseases

  • 1302 Glomerular Diseases: Immunology and Inflammation

Authors

  • Kwon, Eun-Jeong, Seoul National University Bundang Hospital Department of Internal Medicine, Seongnam, Gyeonggi-do, Korea (the Republic of)
  • Chin, Ho Jun, Seoul National University Bundang Hospital Department of Internal Medicine, Seongnam, Korea (the Republic of)
Background

IgM nephropathy (IgMN) is pathologically defined as diffuse deposition of IgM in the mesangium. The definition and characteristics are still unclear. In this study, we explain manifestation of IgMN according to the electron dense deposits (EDD) in mesangium and differences in the clinical feature of IgMN with minimal change disease (MCD) or focal segmental glomerulosclerosis (FSGS). Finally, we would like to compare clinical findings between IgA nephropathy (IgAN) and IgMN, which have mainly mesangial lesions.

Methods

We enrolled 63 adult IgMN patients with a renal biopsy from May 2003 to June 2017. IgMN was defined as 1+ or more IgM antibody deposition in mesangium which intensity is more than the other antibodies of IgG or IgA. We excluded secondary nephropathy: autoimmune diseases, monoclonal gammopathy, or pathologically proven diabetic nephropathy. We compared the characteristics of IgMN with those of 91 MCD, 103 FSGS, and 469 IgAN. The renal failure was defined as decrease of estimated GFR more than 50% at the time of renal biopsy, less than 15 ml/min/1.73 m2, or progressed to end stage renal disease during follow-up period.

Results

There were 13 IgMN patients with EDD and 50 IgMN without EDD. Among light microscopic findings, mesangial cellularity and matrix were increased in IgMN with EDD, more frequently. The intensity of immunofluorescent staining for IgG, IgM, IgA, and C3 were more prominent in IgMN with EDD. Diffuse podocyte effacement was found in IgMN with EDD, more frequently. There was no difference of clinical characteristics and renal outcome of IgMN according to presence of EDD. IgMN had similar clinical features to FSGS. IgMN patients had higher blood pressure, lower proteinuria, and lower level of creatinine at renal biopsy, compared to MCD. However, it is greater blood pressure, creatinine and proteinuria, and more frequent incidence of acute kidney injury at renal biopsy in IgMN compared to IgAN patients. The frequency of renal failure in IgMN (46.0%) was similar to FSGS (40.8 %) (p=0.522), although it was higher than that of MCD (18.7 %) or IgAN (26.4 %) (p<0.001 and p=0.001, respectively).

Conclusion

Clinical characteristics of IgMN were not different according to the presence of EDD. Therefore, IgMN should be defined by the immunofluorescent findings. IgMN has similar characteristics to FSGS, however, has severe presentation compared to MCD and IgAN.