title: Plasma amino acid profiles applied for diagnosis of advanced liver fibrosis in patients with chronic hepatitis C infection.
abstract: Although biopsy has been considered mandatory in diagnosing liver fibrosis, there is a high demand for alternative effective and noninvasive methods. In this study we aimed to develop a noninvasive and effective method using the plasma amino acid profiles for the diagnosis of liver fibrosis.
  
  
  METHODS
  Fifty-three patients with chronic hepatitis C infection were included in the study. Plasma amino acid concentration was analyzed and severity of fibrosis was staged based on biopsy. We employed a previously published amino acid-based approach to develop a discriminator (designated as an "amino-index") for the diagnosis of patients with advanced liver fibrosis. The area under the receiver operating characteristic curve (AUC) was used for evaluation of the diagnosis.
  
  
  RESULTS
  (Phe)/(Val)+(Thr+Met+Orn)/(Pro+Gly) was derived as the optimal amino index. The AUCs were 0.92+/-0.04 (SE) and 0.99+/-0.01 for discriminating advanced fibrosis (fibrosis stages F3 and F4) and for discriminating cirrhosis, respectively. By use of the optimal cut-off values, both the sensitivity and specificity achieved a score over 0.88.
  
  
  CONCLUSIONS
  Fibrosis index based on amino acid concentration could be applied to diagnose liver fibrosis as a convenient noninvasive approach.
authors.affiliation: Pharmaceutical Research Laboratories, Ajinomoto Co. Inc., Kawasaki, Kanagawa, Japan.
authors.forename: Qingwei
authors.initials: Q
authors.lastname: Zhang
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Takahashi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Noguchi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sugimoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kimura
authors.forename: Akihiko
authors.initials: A
authors.lastname: Okumura
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Shinichi
authors.initials: S
authors.lastname: Kakumu