Allopurinol kinetics in humans as a means to assess liver function: evaluation of an allopurinol loading test

A newly developed liver function test was performed on 18 apparently healthy individuals and 29 patients with liver disease. After intravenous injection of a low dose allopurinol (17.1 mumol/kg body mass), blood specimens were collected during 1 h. Plasma analyses of allopurinol and its metabolite oxipurinol were performed and the data were processed by means of a computer-based biodynamic model. This modelling approach makes it possible to estimate parameters, containing information about liver perfusion, hepatocyte membrane transport and hepatocyte cell mass. One parameter (kA31) showed complete discrimination between the reference sample group of healthy individuals and patients with severe liver dysfunction. In a reference sample group of patients with slightly to moderately reduced liver function, only a few patients (5/20) had a kA31 value over the decision limit. In this respect, the allopurinol loading test is superior to the conventional intravenous galactose tolerance test.