title: A shortened, 2-hour rifampin test: a useful tool in Gilbert's syndrome.
abstract: BACKGROUND
  Diagnosis of Gilbert's disease often involves unnecessary testing and patient anxiety. Rifampin test can support the diagnosis; it has been described in short series and lacks standardization in dose, collection times, result presentation and interpretation. Our objective was to compare the response to oral rifampin in a series of patients with Gilbert's disease, 2 and 4 h after drug administration.
  
  
  METHODS
  Eighty-nine patients with Gilbert's disease (elevated total bilirubin with no hepatopathy or hemolysis) were recruited. After a basal blood collection, 900 mg rifampin were administered per os and new samples were drawn 2 and 4 h later. Total and esterified bilirubin were measured in every sample. Haptoglobin concentration was also analyzed.
  
  
  RESULTS
  When expressed as relative increase with respect to basal values, variations observed 2 h after rifampin intake were all above 15%. A significant correlation (r = 0.902; p = 0.000) was found between relative increases 2 and 4 h after drug administration. No significant variations were found in haptoglobin concentrations.
  
  
  CONCLUSIONS
  Rifampin test is useful in diagnosing Gilbert's disease, but variations in total bilirubin concentrations (basal and post-rifampin) make that no absolute cut-off value can be used. Correlation between 2- and 4-h relative increases suggests that a shortened version could simplify the test.
authors.affiliation: Digestive Diseases Section, Hospital General Universitario Morales Meseguer, Murcia, Spain. hassib@ono.com
authors.forename: H
authors.initials: H
authors.lastname: Hallal
authors.forename: J M
authors.initials: JM
authors.lastname: Egea
authors.forename: P
authors.initials: P
authors.lastname: Mas
authors.forename: M D
authors.initials: MD
authors.lastname: García
authors.forename: E
authors.initials: E
authors.lastname: Pérez-Cuadrado
authors.forename: F
authors.initials: F
authors.lastname: Carballo
mesh_terms: D000328:Adult; D001663:Bilirubin / Q000097:blood; D004791:Enzyme Inhibitors; D005878:Gilbert Disease / Q000175:diagnosis*; D006801:Humans; D008875:Middle Aged; D012293:Rifampin
chemical_list: D004791:Enzyme Inhibitors; D001663:Bilirubin; D012293:Rifampin