Monoethylglycinexylide formation in assessing pediatric donor liver function

Lidocaine metabolism to monoethylglycinexylide (MEGX) has been described as a novel method to assess liver function in adult transplant donors and recipients. While this assay appears to offer a number of advantages over existing liver function tests, limited work has been done to evaluate its potential in the pediatric population. This study evaluated MEGX formation in potential pediatric liver donors (n = 35) and a control group of children (n = 16). The mean MEGX formation was significantly higher in pediatric donors than in the control group (156 ± 62 vs 106 ± 33 ng/ml, p < 0.05). No correlation with age, total bilirubin, liver transaminases, or alkaline phosphatase could be made within each group. Significant differences in MEGX levels were noted when each group was compared to its adult counterpart. Both pediatric donors and controls had greater mean MEGX formation than has been reported for adult donors and controls (156 ± 62 vs 127 ± 61 ng/ml, p < 0.05 and 106 ± 33 vs 72 ± 36 ng/ml, p < 0.05, respectively). Drugs that alter lidocaine pharmacokinetics and their potential influence on MEGX formation were evaluated in the pediatric donor group. Donors exposed to hepatic enzyme-inducing drugs had a higher mean MEGX formation (187 ± 60 vs 146 ± 63 ng/ml). No significant differences were noted between donors receiving and not receiving va-sopressors. In conclusion, the significant differences between pediatric and adult MEGX formation should be noted when establishing reference or normal ranges for this diagnostic test. Furthermore, concomitant drug therapy may significantly alter MEGX formation.