title: Establishment of a serum IgG4 cut-off value for the differential diagnosis of IgG4-related sclerosing cholangitis: a Japanese cohort.
abstract: OBJECTIVE
  IgG4-related sclerosing cholangitis (IgG4-SC) must be precisely distinguished from primary sclerosing cholangitis and cholangiocarcinoma (CC) because the treatments are completely different. However, the pathological diagnosis of IgG4-SC is difficult. Therefore, highly specific non-invasive criteria such as serum IgG4 should be established. This study established a cut-off for serum IgG4 to differentiate IgG4-SC from respective controls using serum IgG4 levels measured in Japanese centers.
  
  
  METHODS
  A total of 344 IgG4-SC patients were enrolled in this study. As controls, 245, 110, and 149 patients with pancreatic cancer, primary sclerosing cholangitis, and CC, respectively, were enrolled. IgG4-SC patients were classified into three groups: type 1 (stenosis only in the lower part of the common bile duct), type 2 (stenosis diffusely distributed throughout the intrahepatic and extrahepatic bile ducts), and types 3 and 4 (stenosis in the hilar hepatic region) with 246, 56, and 42 patients, respectively. Serum IgG4 levels were compared, and the cut-offs were established.
  
  
  RESULTS
  The cut-off obtained from receiver operator characteristic curves showed similar sensitivity and specificity to that of 135 mg/dL when all IgG4-SC and controls were compared. However, a new cut-off value was established when subgroups of IgG4-SC and controls were compared. A cut-off of 182 mg/dL can increase the specificity to 96.6% (4.7% increase) for distinguishing types 3 and 4 IgG4-SC from CC. A cut-off of 207 mg/dL might be useful for completely distinguishing types 3 and 4 IgG4-SC from all CC.
  
  
  CONCLUSIONS
  Serum IgG4 is useful for the differential diagnosis of IgG4-SC and controls.
authors.affiliation: Department of Community-Based Medical Education, Nagoya City University Graduate School of Medical Sciences, Nagano, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Ohara
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nakazawa
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Kawa
authors.forename: Terumi
authors.initials: T
authors.lastname: Kamisawa
authors.forename: Tooru
authors.initials: T
authors.lastname: Shimosegawa
authors.forename: Kazushige
authors.initials: K
authors.lastname: Uchida
authors.forename: Kenji
authors.initials: K
authors.lastname: Hirano
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Nishino
authors.forename: Hideaki
authors.initials: H
authors.lastname: Hamano
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kanno
authors.forename: Kenji
authors.initials: K
authors.lastname: Notohara
authors.forename: Osamu
authors.initials: O
authors.lastname: Hasebe
authors.forename: Takashi
authors.initials: T
authors.lastname: Muraki
authors.forename: Etsuji
authors.initials: E
authors.lastname: Ishida
authors.forename: Itaru
authors.initials: I
authors.lastname: Naitoh
authors.forename: Kazuichi
authors.initials: K
authors.lastname: Okazaki
mesh_terms: D000368:Aged; D044466:Asian People; D015415:Biomarkers / Q000097:blood; D015209:Cholangitis, Sclerosing / Q000145:classification / Q000175:diagnosis* / Q000276:immunology; D015331:Cohort Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D007074:Immunoglobulin G