Ammonia produced by the breakdown and metabolism of various amino acids in various tissues of the body and absorbed by the intestinal canal enters the bloodstream, forming blood ammonia. Ammonia is highly toxic to the central nervous system, and high blood ammonia can cause coma. The causes of high blood ammonia are mainly divided into physiological and pathological causes: 1. physiological causes: common after muscle exercise and high protein intake, when the venous blood ammonia is often higher than the arterial blood ammonia; 2. pathological causes: common in hepatic encephalopathy, heavy hepatitis, liver tumors, uremia, congenital hyperammonemia, upper gastrointestinal bleeding, organophosphorus poisoning and congenital ornithine cycle related enzymes Other causes of elevated blood ammonia include unexplained transient elevated blood ammonia in newborns, urinary tract infections, shock, leukemia, heart failure, and other transient elevated blood ammonia. If the blood ammonia is high, we should give active treatment to lower the blood ammonia, firstly, we suggest low protein diet and reduce the amount of high protein food, and secondly, we should go to the hospital promptly and give medication by the doctor’s diagnosis.