The normal value of GGT is between 11 and 50 U/L, which is considered normal in patients with underlying liver disease. However, for some patients with underlying liver disease, such as patients with biliary obstruction, bile stasis, previous tumor disease or stones can cause an increase in GGT. If the total bilirubin and direct bilirubin are elevated, combined with elevated alkaline phosphatase and GGT, the patient should be considered to have biliary obstruction, and further investigation of tumor markers, enhanced MRI or CT of the upper abdomen is needed to determine the cause of biliary obstruction. The most common cause is choledocholithiasis, so ERCP choledocholithiasis extraction and nasobiliary drainage should be actively performed. If GGT is elevated due to neoplastic disease, surgical treatment should be considered as soon as possible.