title: An evaluation of the use of serum 7-alpha-hydroxycholestenone as a diagnostic test of bile acid malabsorption causing watery diarrhea.
abstract: BACKGROUND
  Bile acid malabsorption (BAM) is a recognized cause of watery diarrhea, often diagnosed empirically based on clinical response to cholestyramine. The radionuclide selenium-labelled homocholic acid-taurine whole body retention test is expensive, labour intensive and of limited availability.
  
  
  OBJECTIVE
  To report on the clinical performance of serum 7-alphahydroxy-4-cholesten-3-one (7HCO) as a test of BAM in adult patients with unexplained diarrhea.
  
  
  METHODS
  Patients with unexplained diarrhea were investigated over a three-year period. Final diagnosis was determined based on medical history and investigations, serum levels of 7HCO and response to cholestyramine. ROC analysis was used to determine the ideal upper reference range cut-off value to optimize sensitivity/specificity for BAM. Time of blood specimen collection was recorded to investigate possible variation in results throughout the working day.
  
  
  RESULTS
  ROC analysis yielded a sensitivity/specificity of 90%/77% for type 1 BAM (ileal disease/resection) and 97%/74% for type 2 BAM (idiopathic) using 30 ng/mL as the upper limit of normal for serum 7HCO when compared with all other patients. Of 813 patients, 196 tested positive. Serum 7HCO levels were significantly higher in blood specimens that were collected between 12:00 and 13:00 (median 24 ng/mL) than in specimens collected between 09:00 and 10:00 (median 17 ng/mL) (P<0.05).
  
  
  CONCLUSIONS
  Serum 7HCO testing is a simple, sensitive, noninvasive, inexpensive alternative to other more commonly used tests for BAM. Time of specimen collection, however, resulted in small but significant result variations and, although unlikely to have much impact on test value, it should ideally be standardized.
authors.affiliation: Department of Clinical Biochemistry, Western General Hospital, Edinburgh, UK.
authors.forename: W Gordon
authors.initials: WG
authors.lastname: Brydon
authors.forename: Pearl
authors.initials: P
authors.lastname: Culbert
authors.forename: Kathleen
authors.initials: K
authors.lastname: Kingstone
authors.forename: Ann
authors.initials: A
authors.lastname: Jarvie
authors.forename: Marietta
authors.initials: M
authors.lastname: Iacucci
authors.forename: Merel
authors.initials: M
authors.lastname: Tenhage
authors.forename: Subrata
authors.initials: S
authors.lastname: Ghosh
mesh_terms: D000328:Adult; D000924:Anticholesteremic Agents / Q000008:administration & dosage; D001647:Bile Acids and Salts / Q000378:metabolism*; D002783:Cholestenones / Q000097:blood*; D002792:Cholestyramine Resin / Q000008:administration & dosage; D057186:Comparative Effectiveness Research; D003967:Diarrhea / Q000209:etiology / Q000378:metabolism* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008286:Malabsorption Syndromes / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D012372:ROC Curve; D011877:Radionuclide Imaging; D013997:Time Factors
chemical_list: D000924:Anticholesteremic Agents; D001647:Bile Acids and Salts; D002783:Cholestenones; D002792:Cholestyramine Resin