title: Urine protein patterns can serve as diagnostic tools in patients with IgA nephropathy.
abstract: BACKGROUND
  IgA nephropathy (IgAN) is the most common chronic glomerular disease in adults. End-stage renal disease (ESRD) develops in about 30% of the patients. Early intervention and consequent therapy may prevent or at least delay the development of ESRD in these patients. Up to now, the diagnosis could only be achieved with a renal biopsy.
  
  
  METHODS
  The urine of 45 patients with IgAN was collected and screened for protein/polypeptide patterns with a novel high throughput method, capillary electrophoreses on-line coupled to a mass spectrometer (CE-MS). CE-MS allows the fast and accurate evaluation of up to 2000 polypeptides in one urine sample. The results in IgAN were compared to findings in 13 patients with membranous nephropathy (MN) and 57 healthy individuals.
  
  
  RESULTS
  In the patients with IgAN, even when urinary protein excretion was within the normal range of regular tests, the polypeptide pattern in urine differed significantly from that of healthy controls and patients with MN, indicating a specific "IgAN" pattern of polypeptide excretion. Classification regarding discrimination of IgAN from healthy controls and from MN had a sensitivity of 100% and 77%, respectively. Specificity was 90% and 100%, respectively. Compared to patterns established earlier in patients with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), or diabetic nephropathy (DN), sensitivity and specificity were 100%. Treatment of the patients was associated with changes of the pattern, possibly indicating a therapeutic effect.
  
  
  CONCLUSIONS
  Proteomic analysis with CE-MS coupling permits fast and accurate identification and differentiation of polypeptide patterns in the urine of patients with IgAN, allowing differentiation from healthy controls and, probably, other renal diseases.
authors.affiliation: Department of Nephrology, Hannover Medical School, Hannover, Germany. Haubitz.Marion@MH-Hannover.de
authors.forename: Marion
authors.initials: M
authors.lastname: Haubitz
authors.forename: Stefan
authors.initials: S
authors.lastname: Wittke
authors.forename: Eva M
authors.initials: EM
authors.lastname: Weissinger
authors.forename: Michael
authors.initials: M
authors.lastname: Walden
authors.forename: Harald D
authors.initials: HD
authors.lastname: Rupprecht
authors.forename: Jürgen
authors.initials: J
authors.lastname: Floege
authors.forename: Hermann
authors.initials: H
authors.lastname: Haller
authors.forename: Harald
authors.initials: H
authors.lastname: Mischak
mesh_terms: D000328:Adult; D000368:Aged; D019075:Electrophoresis, Capillary; D005260:Female; D005922:Glomerulonephritis, IGA / Q000175:diagnosis* / Q000652:urine; D015433:Glomerulonephritis, Membranous / Q000175:diagnosis / Q000652:urine; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D011507:Proteinuria / Q000652:urine*; D040901:Proteomics; D012680:Sensitivity and Specificity