title: Serum IgA/C3 ratio may be a useful marker of disease activity in severe Henoch-Schönlein nephritis.
abstract: OBJECTIVE
  This study was designed to investigate whether the serum IgA/C3 ratio can be a serologic marker of disease activity in children with severe Henoch-Schönlein nephritis (HSN).
  
  
  METHODS
  Twelve HSN patients who were treated with steroids and cyclosporine were examined. The levels of serum IgA and C3 were measured using an international reference preparation (IFCC/CRM470) and a renal biopsy was performed in all patients before and after therapy. After therapy, patients were divided into 3 groups: complete remission (n = 6, group I), mild urinary abnormalities (n = 3, group II), and active renal disease (n = 3, group III).
  
  
  RESULTS
  The serum IgA/C3 ratio decreased significantly in groups I and II after therapy (2.62 +/- 0.82 vs. 2.02 +/- 0.52, p = 0.02), whereas the ratio in group III increased, although it was not statistically significant (2.13 +/- 0.93 vs. 4.67 +/- 1.71, p = 0.25). A follow-up renal biopsy revealed that the activity index was reduced in groups I and II (7.0 +/- 2.4 vs. 3.6 +/- 1.6, p = 0.016), and not changed in group III (7.3 +/- 2.1 vs. 9.3 +/- 2.5, p = 0.25). The activity index at a follow-up renal biopsy correlated positively with the changes of the serum IgA/C3 ratio: posttherapy activity index = 1.20 x DeltaIgA/C3 + 4.78 (r = 0.635, p = 0.027); where DeltaIgA/C3 is posttherapy IgA/C3--pretherapy IgA/C3.
  
  
  CONCLUSIONS
  These findings suggest that the serum IgA/C3 ratio may be a useful marker to predict disease activity and histologic severity in HSN.
authors.affiliation: Department of Pediatrics, Institute of Kidney Disease, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jae Il
authors.initials: JI
authors.lastname: Shin
authors.forename: Jee Min
authors.initials: JM
authors.lastname: Park
authors.forename: Youn Ho
authors.initials: YH
authors.lastname: Shin
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Lee
authors.forename: Hyeon Joo
authors.initials: HJ
authors.lastname: Jeong
authors.forename: Hyon Suk
authors.initials: HS
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D003176:Complement C3 / Q000032:analysis*; D005260:Female; D006801:Humans; D011695:IgA Vasculitis / Q000097:blood* / Q000150:complications / Q000473:pathology; D007070:Immunoglobulin A / Q000097:blood*; D008297:Male; D009393:Nephritis / Q000097:blood* / Q000150:complications / Q000473:pathology; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers; D003176:Complement C3; D007070:Immunoglobulin A