Normal values for blood ammonia range from 18-72 umol/L and are used as an indicator of the liver. If a patient’s examination reveals elevated blood ammonia, it is considered to be caused by a disease of the liver. It is commonly found in various viral hepatitis, liver cancer, cirrhosis, etc., which may cause elevated blood ammonia. Patients are advised to go to a regular tertiary hospital for further detailed examination and treatment after a clear diagnosis if they find elevated blood ammonia in blood tests. However, in each region or each hospital, the examination items and instruments used are different, which may cause the normal range of the patient’s blood ammonia to be different. It is recommended to make reference to the normal values on the laboratory test, and consult a doctor in the hospital if necessary, to avoid blind guessing, in order to prevent changes in the condition.