Human serum glucose-6-phosphatase activity: Confirmation of its presence and lack of diagnostic value

A study was made of glucose-6-phosphate (G-6-P) hydrolysis by serum from patients with infectious hepatitis, obstructive jaundice, or bone disease, and a normal control group. Two methods of measuring G-6-P hydrolysis were used; one measured glucose liberated under conditions specific for glucose-6-phosphatase (G-6-Pase), the other measured phosphate release under conditions that did not distinguish hydrolysis due to non-specific phosphatases from that due to G-6-Pase. The specific G-6-Pase assay showed a highly significant difference between normal subjects and patients with infectious hepatitis but not between normals and patients with obstructive jaundice or bone disease. When phosphate release was measured no significant difference was found between normals and patients with infectious hepatitis or bone disease but a highly significant difference was found between the normal and obstructive jaundice groups. The existence of serum glucose-6-phosphatase is confirmed in patients with infectious hepatitis. Low serum activities and overlap between normal and abnormal subjects make the test of little routine value.