title: [Clinical significance of detection of plasma and urine IgG4 in idiopathic membranous nephropathy].
abstract: OBJECTIVE
  To investigate the possibility of IgG4/IgG as one of biomarkers to reflect disease activity and the relapse of idiopathic membranous nephropathy (IMN).
  
  
  METHODS
  Plasma and urine samples were obtained from patients with IMN (Twenty-four patients had follow-up data), minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) before immunosuppressive therapy. Concentrations of plasma and urine IgG4 and total IgG were detected by sandwich ELISA. The ratio of IgG4/IgG was calculated as the concentration of IgG4 divided by total IgG.
  
  
  RESULTS
  Both plasma and urine IgG4/IgG ratios were significantly higher in IMN group compared with MCD or FSGS group (both P<0.05). In IMN, both plasma and urine IgG4/IgG ratios in patients with nephritic syndrome were significantly higher versus those with subnephrotic proteinuria (P=0.063; P<0.05). Both plasma and urine IgG4/IgG ratios were significantly decreased with remission (P<0.05) and maintained or even increased with resistance to therapy. Patients who relapsed within 2 years had higher urine IgG4/IgG-ratios than those who had no relapse (P<0.05), and patients with urine IgG4/IgG-ratios≥9% upon renal biopsy had higher relapse tendency (P=0.071).
  
  
  CONCLUSIONS
  Both plasma and urine IgG4/IgG ratios might be a promising biomarker to reflect disease activity of IMN, and higher urine IgG4/IgG ratios might suggest higher relapse tendency.
authors.affiliation: Department of Nephrology, Peking University First Hospital, Institute of Nephrology, Peking University, Beijing 100034, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Zhen
authors.initials: Z
authors.lastname: Qu
authors.forename: Yi-miao
authors.initials: YM
authors.lastname: Zhang
authors.forename: Feng
authors.initials: F
authors.lastname: Yu
authors.forename: Jing
authors.initials: J
authors.lastname: Huang
authors.forename: Rui
authors.initials: R
authors.lastname: Yang
authors.forename: Ming-hui
authors.initials: MH
authors.lastname: Zhao
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood / Q000652:urine; D005260:Female; D015433:Glomerulonephritis, Membranous / Q000097:blood / Q000276:immunology* / Q000652:urine; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood* / Q000652:urine*; D008297:Male; D008875:Middle Aged
chemical_list: D015415:Biomarkers; D007074:Immunoglobulin G