title: Brown pigment stones in the common bile duct: reduced bilirubinate diconjugate in bile.
abstract: BACKGROUND
  Bilirubin is the main component of most common bile duct stones. Normally, almost all bilirubin in bile is conjugated to glucuronic acid or some other sugar moiety. These conjugates are unstable and liable to deconjugation. Unconjugated bilirubin is insoluble and may precipitate as the calcium salt found in brown pigment stones. The pattern of bilirubin conjugates in common duct bile of patients with choledocholithiasis has been unknown.
  
  
  METHODS
  In a clinical series of 55 patients with choledocholithiasis common-duct bile was aspirated, and the bilirubin conjugates analyzed with high-performance liquid chromatography. One stone from each patient was analyzed for cholesterol and bilirubin content to determine stone type.
  
  
  RESULTS
  Sixteen patients had cholesterol stones, 38 patients had brown pigment stones, and 1 patient had a black stone. Patients with pigment stones had a lower percentage of bilirubin diglucuronide (median, 60.3%; interquartile range, 49.7%-67.3%) than patients with cholesterol stones (64.0%; 60.2%-73.3%) (Mann-Whitney, P=0.015). No significant difference was found for the other bilirubin conjugates, total bilirubin, or biliary pH when pigment and cholesterol stone patients were compared. The time of bile sampling in relation to papillotomy and treatment of cholestasis was not associated with the low percentage of bilirubin diglucuronide. The observation of reduced values for bilirubin diglucuronide could not be ascribed to duodenal diverticula or Billroth-II gastric resection.
  
  
  CONCLUSIONS
  The percentage of the main bilirubinate conjugate, bilirubin diglucuronide, is decreased in the common duct bile of patients with pigmented compared with cholesterol stones.
authors.affiliation: Dept. of Internal Medicine, Ullevål Hospital, Oslo, Norway.
authors.forename: O
authors.initials: O
authors.lastname: Sandstad
authors.forename: T
authors.initials: T
authors.lastname: Osnes
authors.forename: P
authors.initials: P
authors.lastname: Urdal
authors.forename: V
authors.initials: V
authors.lastname: Skar
authors.forename: M
authors.initials: M
authors.lastname: Osnes
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001646:Bile / Q000737:chemistry* / Q000378:metabolism; D001654:Bile Pigments; D001663:Bilirubin / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism*; D002137:Calculi / Q000737:chemistry* / Q000145:classification; D002853:Chromatography, Liquid; D005260:Female; D042882:Gallstones / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D001654:Bile Pigments; C019270:bilirubin diglucuronide; D001663:Bilirubin