title: High serum C3 predicts poor outcome in IgM nephropathy.
abstract: BACKGROUND
  IgM nephropathy (IgMN) is an idiopathic glomerulonephritis with mesangial IgM deposition. The etiology of the depositions and possible association of serum and mesangial immunoglobulins and complement findings with renal outcome in IgMN remain unknown. Here we brought out data supplementary to our previous findings by reporting associations of immunological parameters with the outcome of IgMN.
  
  
  METHODS
  Serum IgA, IgG, IgM, C3 and C4 were measured in 110 IgMN patients by single radial immunodiffusion or nephelometry. Mesangial IgA, IgG, IgM, C1q and C3 assessed in immunofluorescent study were graded as +/-. Seven histopathological parameters were semiquantitatively graded into three classes. The relationship of serum and mesangial immunoglobulin and complement findings with the clinical outcome and prognosis of IgMN was examined.
  
  
  RESULTS
  We found significantly lower serum IgG and higher serum C3 levels in patients with nephrotic syndrome. Serum C3 correlated with the severity of glomerular histopathological changes. Of immunological parameters evaluated a low serum IgG/C3 ratio correlated best with the progression of renal disease. However, serum C3 was associated independently with progression in the case of patients without nephrotic syndrome.
  
  
  CONCLUSIONS
  In addition to previously reported factors, immunological parameters may also be helpful in determining the prognosis in IgMN. High serum C3 predicts poor outcome in IgMN, being associated with high-grade proteinuria, severe histopathological changes and progression.
authors.affiliation: Medical School, University of Tampere, Tampere, Finland.
authors.forename: Juhani
authors.initials: J
authors.lastname: Myllymäki
authors.forename: Heikki
authors.initials: H
authors.lastname: Saha
authors.forename: Amos
authors.initials: A
authors.lastname: Pasternack
authors.forename: Heikki
authors.initials: H
authors.lastname: Helin
authors.forename: Jukka
authors.initials: J
authors.lastname: Mustonen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003176:Complement C3 / Q000032:analysis*; D005260:Female; D005921:Glomerulonephritis / Q000097:blood* / Q000276:immunology*; D006801:Humans; D007075:Immunoglobulin M; D007223:Infant; D008297:Male; D008875:Middle Aged; D011379:Prognosis
chemical_list: D003176:Complement C3; D007075:Immunoglobulin M