The diagnostic potential of the combined determination of serum monoamine oxidase and N-acetyl-beta-D-glucosaminidase for fibroproliferative liver diseases.

The simultaneous determination of the catalytic activities in serum of monoamine oxidase (EC 1.4.3.4) and N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30) was performed in patients with various non-liver diseases, acute hepatitis and fibroproliferative liver disorders (cirrhosis and fibrosis) and the predictive values of the positive (both activities are pathologically elevated) and negative test results (normal activity of monoamine oxidase and/or N-acetyl-beta-D-glucosaminidase) were estimated. It was found that the incidence of the positive result is extremely low (0.024, 5/207) in patients suffering from a great variety of non-liver and liver diseases (except cirrhosis) but rather great in liver cirrhotic subjects (0.44, 18/41). A fraction of only 0.07 of liver fibrotic patients had a positive test result. Based on these data the estimated predictive value of the positive result for liver cirrhosis at a prevalence of 0.03 is 0.47. This value increases strongly with higher prevalence of cirrhosis (population preselected for chronic liver diseases). The negative predictive value for cirrhosis and the positive value for fibrosis are low. Thus, the probability of the presence of cirrhosis in patients with suspected chronic liver diseases is great in cases of abnormally high activities of both monoamine oxidase and N-acetyl-beta-D-glucosaminidase. Negative test results (normal catalytic activities of one or both enzymes), however, do not prove the absence of liver cirrhosis and/or liver fibrosis.