title: The monoethylglycinexylidide test for grading of liver cirrhosis.
abstract: BACKGROUND
  Monoethylglycinexylidide (MEGX) formation following lignocaine injection has recently been proposed as a simple dynamic liver function test based on a single measurement of its serum concentration.
  
  
  OBJECTIVE
  To determine the optimal sampling time for MEGX determination.
  
  
  METHODS
  A modelling analysis of lignocaine and MEGX kinetics was performed in seven normals and in four patients with compensated liver cirrhosis; a similar study was performed in 74 cirrhotic patients, divided into two groups according to disease severity (Pugh score).
  
  
  RESULTS
  Only the MEGX fractional formation rate (kf) and formation delay (tau) were significantly altered in cirrhotic patients compared to normals: kf = 0.15 +/- 0.03 vs. 0.32 +/- 0.10 min-1 (mean +/- s.d.); tau = 7.7 +/- 2.0 vs. 3.9 +/- 2.9 min-1. A good correlation was found between kf and late (r = 0.82) but not early (r = 0.63) serum MEGX formation, suggesting that late measurements for the clinical MEGX test are preferred. In the second part of our investigation, by discriminant analysis of MEGX test data for 74 cirrhotic patients, the late MEGX concentrations gave the best discrimination between the two classes. In particular, the 60 min MEGX concentration showed the best diagnostic accuracy (81%), sensitivity (75%) and specificity (84%). The association of this with other MEGX parameters, either singly or derived from the whole curve measurements, did not improve the performance of the method.
  
  
  CONCLUSIONS
  The MEGX test, based on a single determination 60 min after lignocaine injection, may be regarded as a simple and sensitive quantitative liver function test.
authors.affiliation: Istituto di Medicina Interna, Università di Padova, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Fabris
authors.forename: R M
authors.initials: RM
authors.lastname: Jemmolo
authors.forename: G
authors.initials: G
authors.lastname: Toffolo
authors.forename: D
authors.initials: D
authors.lastname: Paleari
authors.forename: S
authors.initials: S
authors.lastname: Viaggi
authors.forename: M
authors.initials: M
authors.lastname: Rigon
authors.forename: F
authors.initials: F
authors.lastname: Casagrande
authors.forename: F
authors.initials: F
authors.lastname: Lirussi
authors.forename: M
authors.initials: M
authors.lastname: Strazzabosco
authors.forename: C
authors.initials: C
authors.lastname: Cobelli
authors.forename: L
authors.initials: L
authors.lastname: Okolicsanyi
mesh_terms: D000328:Adult; D016002:Discriminant Analysis; D005260:Female; D006801:Humans; D008012:Lidocaine / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D008103:Liver Cirrhosis / Q000145:classification* / Q000175:diagnosis*; D008111:Liver Function Tests / Q000379:methods; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D012680:Sensitivity and Specificity
chemical_list: D008012:Lidocaine; C001173:monoethylglycinexylidide