Kits for enzyme determinations compared: relation between composition and quality

Kits of five different suppliers, composed according to the Dutch recommendations for determination of the enzyme activity of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, gamma-glutamyltransferase, alkaline phosphatase, and creatine kinase, were intercompared. Activity concentrations of the enzymes in human sera were measured under defined conditions, evaluated, and related to the actual composition of the kits. Concentrations of all kit components were determined by various analytical techniques. The overall results of the activity measurements and the composition of at least three kits inter-agree well. We found deviations as great as 10% in our analytical evaluation of the kits of the other two suppliers, which can partly be accounted for.