title: Intermethod calibration of alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT) results: application to Fibrotest and Actitest scores.
abstract: Two multi-component scores (Fibrotest and Actitest) have been proposed to evaluate liver fibrosis or necro-inflammatory lesions as an alternative to liver biopsy. This approach requires standardization of alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT) determinations. For this purpose, ALT and GGT values were assigned to a multi-enzyme material using the appropriate primary reference procedure. This material was used as a common calibrator for sera from 20 patients with viral hepatitis. Measurements were carried out in 11 laboratories, using their own automated routine methods and compared to results obtained using the primary reference procedure. The expression of results in multiples of the upper reference limit worsened the inter-laboratory variation for both enzymes. The multi-enzyme material was commutable for ALT and GGT determination carried out with six analytical systems. Common calibration significantly improved inter-laboratory consistency, which finally reached 1.8% and 3.3% for ALT and GGT, respectively. For each enzyme, it also permitted the retention of a common reference interval for a set of calibrated methods and the improvement of inter-laboratory coherency of Fibrotest and Actitest scores.
authors.affiliation: Faculté de Pharmacie, Université Louis Pasteur de Strasbourg, Illkirch, France.
authors.forename: Georges
authors.initials: G
authors.lastname: Férard
authors.forename: Annie
authors.initials: A
authors.lastname: Piton
authors.forename: Djamila
authors.initials: D
authors.lastname: Messous
authors.forename: Françoise
authors.initials: F
authors.lastname: Imbert-Bismut
authors.forename: Asmaa
authors.initials: A
authors.lastname: Frairi
authors.forename: Thierry
authors.initials: T
authors.lastname: Poynard
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Lessinger
mesh_terms: D000328:Adult; D000368:Aged; D000410:Alanine Transaminase / Q000097:blood / Q000592:standards*; D002138:Calibration; D004796:Clinical Enzyme Tests / Q000592:standards*; D005260:Female; D005355:Fibrosis / Q000175:diagnosis; D006505:Hepatitis / Q000097:blood / Q000473:pathology; D006801:Humans; D007249:Inflammation / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012015:Reference Standards; D005723:gamma-Glutamyltransferase / Q000097:blood / Q000592:standards*
chemical_list: D005723:gamma-Glutamyltransferase; D000410:Alanine Transaminase