The normal range of blood ammonia is 18-72umol/L, which is used as an indicator of the liver. If elevated blood ammonia is found during a patient’s examination, it is considered to be caused by some disease of the liver. This is commonly seen in various viral hepatitis, liver cancer, and cirrhosis, all of which may cause elevated blood ammonia. Patients are advised to go to a regular tertiary care hospital for further detailed examination if they find elevated blood ammonia in blood tests, and to actively treat the disease after a clear diagnosis. However, the normal range of blood ammonia may vary from region to region or from hospital to hospital, depending on the test items and instruments used. It is recommended to make reference to the normal value on the laboratory test sheet, and to consult the doctor at the hospital if necessary to avoid blind guesses to prevent changes in the condition.