Application of a Continuous Spectrophotometric Assay for 5'Nucleotidase Activity in Normal Subjects and Patients with Liver and Bone Disease

Abstract

Abstract Serum 5'nucleotidase activity has been measured by a coupled kinetic assay in which adenosine formed by hydrolysis of adenosine 5'-monophosphate in the presence of 150-fold excess of β-glycerophosphate is converted to inosine by adenosine deaminase, with a consequent decrease in absorbance at 265 nm. The method gives activity in proportion to enzyme concentration so long as the rate of decrease of absorbance at 265 nm does not exceed 0.025/min, and not more than 30% of the substrate is consumed. The normal range established in 517 healthy adults was 0-15 mU/ml. A significant correlation between enzyme activity and age was found in females but not in males. Raised levels of 5'nucleotidase activity were found in 92% of patients with obstructive jaundice, 70% of patients with parenchymal liver disease, 81% of patients with hepatic metastases, and 11% of patients with bone disease. The estimation is useful in aiding the elucidation of raised serum alkaline phosphatase activity, and is of value as a liver function test, but is not as frequently increased as alkaline phosphatase in all classes of hepatobiliary disease.