Glutamyl transpeptidase 300+ may be caused by bile duct obstruction, viral hepatitis, cirrhosis and liver cancer. 1. Bile duct obstruction: elevated glutamyl transpeptidase usually reflects liver cell damage. When the bile duct is obstructed, the pressure in the bile duct is elevated, and there may be bile reflux, which causes liver cell damage. Therefore, glutamyl transpeptidase 300+ may be caused by bile duct obstruction. 2. Viral hepatitis: when liver inflammation occurs due to viral attack, under the action of virus and inflammatory mediators released by inflammatory cells, it may cause hepatocyte injury, thus the situation of glutamyl transpeptidase 300+ occurs. 3. Hepatocellular carcinoma: when malignant tumors occur in the liver, liver cell damage may also occur, thus leading to glutamyl transpeptidase 300+. When glutamyl transpeptidase 300 or more occurs, you should consult a doctor in time and improve ultrasound, pathogen serology examination, abdominal CT and other examinations under the doctor’s guidance, so as to clarify the cause of the disease and treat it positively.