USE OF HEPATIC LIDOCAINE METABOLISM TO MONITOR PATIENTS WITH CHRONIC LIVER-DISEASE

Lidocaine is converted to its primary metabolic product monoethylglyci nexylodide (MEGX) via cytochrome P-4503A4 within the liver. A steady-s tate concentration of MEGX appears in serum within 15 min following th e intravenous administration of lidocaine. The present article reviews some of the data suggesting that this MEGX value can be utilized to a ssess hepatic function. MEGX production declines stepwise with the sev erity of chronic hepatitis. In patients with cirrhosis, MEGX declines further with worsening Child class. Nearly all persons with MEGX of <2 0 ng/ml had cirrhosis confirmed upon histologic evaluation. Severe lif e-threatening complications of cirrhosis were observed only in patient s with MEGX production below 20 ng/ml. One-year survival for patients with an MEGX value of <10 ng/ml was only 50%. In contrast, 1-year surv ival for patients with MEGX of >10 ng/ml was similar to 80%. These dat a suggest that MEGX could be utilized as an accurate test of hepatic f unction and to predict morbidity and mortality related to complication s of chronic liver disease. However, this test does have several limit ations. There is wide interpatient variability between MEGX and hepati c histology, which severely impairs the ability of this test to accura tely predict hepatic histology. In addition, MEGX is affected by gende r and several medications. However, since MEGX does decline stepwise w ith advancing histology in any given patient, the available data sugge st that serial monitoring of MEGX could be utilized to track hepatic m etabolic capacity in patients with chronic hepatitis and cirrhosis.