title: L-[1-13C] phenylalanine breath test reflects histological changes in the liver.
abstract: OBJECTIVE
  Compared with healthy individuals, patients with chronic liver disease reportedly have lower L-[1-13C] phenylalanine breath test (PBT) values. However, there is no report detailing the relationship between the results of PBT and pathological data in liver disease patients. This study was designed to investigate the degree of histological changes in the liver that induce PBT changes and the time of measurement that reflects the histological change.
  
  
  METHODS
  PBT was performed in 47 patients (10 with a normal liver, and 37 with chronic hepatitis C). After administering 10 mg/kg L-[1-13C] phenylalanine, 300 mL of expired air was collected over 90 min at 15-min intervals. The rate of hepatic phenylalanine oxidation (%13C dose h(-1)) at each time point was calculated from the amount of 13CO(2) in the exhaled air, assuming a CO(2) production rate of 300 mmol m(-2) body surface area per hour. Subsequently, we examined the relationship between the results of PBT and METAVIR pathological scoring.
  
  
  RESULTS
  The highest correlation coefficients between the fibrosis score and %13C dose h(-1) and between the fibrosis score and %13C cumulative excretion were obtained at 45 min (r = -0.779, R(2) = 0.607; P < 0.0001) and 75 min (r = -0.768, R(2) = 0.590; P < 0.0001), respectively.
  
  
  CONCLUSIONS
  PBT is a useful adjunct for detecting histological changes in the liver. The %13C dose h(-1) value at 45 min and the %13C cumulative excretion value at 75 min of PBT are useful for detecting hepatic histological change.
authors.affiliation: Medical Research Center, Division of Genetic and Genomic Research, Nihon University School of Medicine, Itabashi-ku, Tokyo 173-8610, Japan. yishii@med.nihon-u.ac.jp
authors.forename: Yukimoto
authors.initials: Y
authors.lastname: Ishii
authors.forename: Shigeru
authors.initials: S
authors.lastname: Suzuki
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Kohno
authors.forename: Masaru
authors.initials: M
authors.lastname: Aoki
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kohno
authors.forename: Asuka
authors.initials: A
authors.lastname: Ito
authors.forename: Tadatoshi
authors.initials: T
authors.lastname: Takayama
authors.forename: Satoshi
authors.initials: S
authors.lastname: Asai
mesh_terms: D015415:Biomarkers; D001944:Breath Tests; D002247:Carbon Isotopes; D018937:Hepatitis C Antibodies / Q000097:blood; D019698:Hepatitis C, Chronic / Q000473:pathology* / Q000601:surgery; D006801:Humans; D008099:Liver / Q000473:pathology*; D008103:Liver Cirrhosis / Q000209:etiology / Q000473:pathology / Q000601:surgery; D010649:Phenylalanine / Q000032:analysis*; D012016:Reference Values; D013274:Stomach Neoplasms / Q000473:pathology* / Q000601:surgery*; D013997:Time Factors
chemical_list: D015415:Biomarkers; D002247:Carbon Isotopes; D018937:Hepatitis C Antibodies; D010649:Phenylalanine