The monoethylglycinexylidide test for grading of liver cirrhosis

Background: Monoethylglycinexylidide (MEGX) formation following lignocaine injection has recently been proposed as a simple dynamic liver function tes t based on a single measurement of its serum concentration. Aim: 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 grou ps according to disease severity (Pugh score). Results: Only the MEGX fractional formation rate (k(f)) and formation delay (tau) were significantly altered in cirrhotic patients compared to normals : k(f) = 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 k(f) and late (r = 0.82) but not early (r = 0.63) serum MEGX formation, suggest ing that late measurements for the clinical MEGX test are preferred. In the second part of our investigation, by discriminant analysis of MEGX test da ta for 74 cirrhotic patients, the late MEGX concentrations gave the best di scrimination between the two classes. In particular, the 60 min MEGX concen tration showed the best diagnostic accuracy (81%), sensitivity (75%) and sp ecificity (84%). The association of this with other MEGX parameters, either singly or derived from the whole curve measurements, did not improve the p erformance of the method. Conclusion: The MEGX test, based on a single determination 60 min after lig nocaine injection, may be regarded as a simple and sensitive quantitative l iver function test.