Clinical significance of catalytic serum adenosine deaminase activity determination for differentiation of hepatocellular and obstructive icterus

Adenosine deaminase (ADA, E C 3.5.4.4) catalyzes adenosine deamination producing inosine and releasing ammonia. Due to ist role in purine metabolism this enzyme is widely distributed in animal and most of the human tissues. Concentration of ADA catalytic activity in the serum was found to be increased in several human diseases such as hepatic disorders, infectious mononucleosis, typhoid, acute leucemia and sarcoidosis. The aim of the present study was to find out whether there are the differences in catalytic serum ADA concentrations in the case of hepatocellular and obstructive icterus. The group of examinees included 13 patients suffering from obstructive icterus and 18 patients with acute viral hepatitis. The group consisting of 15 healthy Volunteers of the matched age served as the control. Serum level of catalytic activity of the following enzymes was determined: ADA, aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (AP). Activity of ADA was measured by a modified method according to Giusti. Activity of ADA in the control group that served as reference was 54,03+/-296 nkat/L. Mean value of ADA catalytic activity in the sera of the patients suffering from acute virus hepatitis (316,96+/-256 nkat/L) significantly exceeded control value (p<0.001). In the patients with obstructive icterus, however, only a slight elevation of ADA activity (78+/-37,18 nkat/L) in relation to healthy controls was recorded. At the same time, serum BST, ALT and AP activities were significantly increased in both groups of icteric patients in comparison with the control. The results obtained throughout the present study suggest that determination of serum ADA activity could be of a certain diagnostic value to differentiate among obstructive and hepatocellular icterus.