title: IgG4 Levels in Bile for Distinguishing IgG4-Associated Cholangiopathy from Other Biliary Disorders: A Single Blinded Pilot Study.
abstract: OBJECTIVE
  Immunoglobulin G4 (IgG4)-associated cholangiopathy (IAC) is an inflammatory disease and may mimic primary sclerosing cholangitis (PSC), cholangiocarcinoma (CCA), or pancreatic cancer on cholangiography. We investigated whether IgG4 levels in bile aspirated during endoscopic retrograde cholangiopancreatography (ERCP) can distinguish IAC from PSC, CCA, and pancreatic cancer.
  
  
  METHODS
  Bile was aspirated directly from the common bile duct during ERCP in patients with IAC prior to steroid therapy. For control purposes, bile was obtained from patients with PSC, CCA, pancreatic cancer, and benign biliary conditions (sphincter of oddi dysfunction/choledocholithiasis).
  
  
  RESULTS
  Biliary IgG4 levels were measured in 54 patients. The median bile IgG4 levels were markedly elevated in patients with IAC (5.5 mg/dL; interquartile range [IQR], 5.1 to 15.6) as compared to patients with benign biliary conditions (0 mg/dL; IQR, 0 to 0.1; p=0.003). The median biliary IgG4 levels in PSC, CCA, and pancreatic cancer were 1.2 (IQR, 0.2 to 3.8), 0.9 (IQR, 0.2 to 3.4), and 0.2 mg/dL (IQR, 0.1 to 0.8), respectively. A cutoff value of 3.8 mg/dL distinguished IAC from PSC and CCA patients with 100% and 76.9% sensitivity and specificity, respectively.
  
  
  CONCLUSIONS
  The results of this pilot study suggest that measurement of biliary IgG4 levels may have clinical value in distinguishing patients with IAC from biliary disorders that can mimic IAC.
authors.affiliation: Department of Gastroenterology, Digestive Disease Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Udayakumar
authors.initials: U
authors.lastname: Navaneethan
authors.affiliation: Department of Gastroenterology, Digestive Disease Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Norma G
authors.initials: NG
authors.lastname: Gutierrez
authors.affiliation: Department of Gastroenterology, Digestive Disease Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Ramprasad
authors.initials: R
authors.lastname: Jegadeesan
authors.affiliation: Department of Gastroenterology, Digestive Disease Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Preethi Gk
authors.initials: PG
authors.lastname: Venkatesh
authors.affiliation: Hybridoma Core Laboratory, Lerners Research Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Earl
authors.initials: E
authors.lastname: Poptic
authors.affiliation: Department of Gastroenterology, Digestive Disease Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Madhusudhan R
authors.initials: MR
authors.lastname: Sanaka
authors.affiliation: Department of Gastroenterology, Digestive Disease Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: John J
authors.initials: JJ
authors.lastname: Vargo
authors.affiliation: Department of Gastroenterology, Digestive Disease Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Mansour A
authors.initials: MA
authors.lastname: Parsi
keywords: Bile; Cholangiopancreatography, endoscopic retrograde; Immunoglobulin G