Clinical evaluation of serum guanase activity in liver diseases

We measured serum guanase (EC 3.5.4.3) activity in patients with various diseases and in healthy controls, and evaluated the clinical usefulness of this enzyme in liver diseases. The reference range, which showed no significant difference between sexes and ages over the range studied, was 0 to 1.8 U/L. The mean guanase activities for patients with various liver diseases, including acute hepatitis, chronic hepatitis, liver cirrhosis, hepatoma and metastatic carcinoma, were above the upper limit of the reference range. In acute hepatitis and metastatic carcinoma of the liver, the activities were especially high. Validity (sensitivity + specificity) of guanase, which in all tests was above 1.66, was compared to that of AST and ALT in liver diseases. With guanase, the highest validity (1.98) was found in acute hepatitis and metastatic carcinoma. Specificity of guanase was 0.98, whereas sensitivity of AST was 1.00 in all diseases. Sensitivity and specificity of ALT were 0.85 to 0.97 in all diseases. As guanase was specific, including this enzyme with other liver function tests, such as AST and ALT, may decrease false-positive results and may be effective for prediction of liver disease.