Usefulnessof Serum NucleotidePyrophosphataseand PhosphodiesteraseI

activities were determined in sera from 126 patients with different types of liver disease and in two additional groups of patients with intra- and extrahepatic cholestasis, re-spectively. Both activities probably represent the same enzyme, and were positively correlated with alkaline phosphatase, lipoprotein X, and several other tests re-flecting cholestasis. Also, we found by discriminant analysis that tests for cholestasis frequently replaced the results for both enzymes. In some groups of liver disease, nucleotide pyrophosphatase and phosphodiesterase I were correlated with the concentrations of prealbumin and al-bumin. The sensitivity of phosphodiesterase I (and nude-otide pyrophosphatase) is rather low when compared with alkaline phosphatase, and we do not recommend it for use in the clinical routine. Nevertheless, it appears to be of potential value for studies on classification of liver dis-eases, adding information to a panel of 20 commonly used “liver tests ” by appearing in some of the best four test-sets for distinguishing between groups of liver disease by discriminant analysis. AdditIonal Keyphrases enzymic assays. discriminant analysis. diagnostic test panels. cholestasis reference intervals Nucleotide pyrophosphatase (EC 3.6.1.9) and phosphodi-esterase I (EC 3.1.4.1) are present in normal serum from hu-mans and various animals (1-4). In preliminary studies, in-creased activities have been found during normal pregnancy (1), in some types of cancer (1, 2), and in cholestatic liver disease (1,2,5). We report here our evaluation of the use of serum nucleotide pyrophosphatase and phosphodiesterase I activities in diag-nosis and classification of liver disease