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 μmol/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 (k_A31) 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 k_A31 value over the decision limit. In this respect, the allopurinol loading test is superior to the conventional intravenous galactose tolerance test.