There are many reasons for elevated blood ammonia, the main reasons are severely impaired liver function, formation of portal shunt in cirrhosis, and upper gastrointestinal bleeding, as follows: 1. Severely impaired liver function: Because the liver is a detoxification organ, the nitrogen produced after protein decomposition and metabolism must be excreted in the liver to form urea. If liver function is impaired, nitrogen cannot form urea and is excreted directly into the intestinal cavity, ammonia will be formed under the action of bacteria such as intestinal tract, and ammonia is absorbed into the blood, which will cause elevated blood ammonia. 2. Portal shunt formation in cirrhosis: ammonia from the intestine is not metabolized by the liver, but directly enters the body circulation, which will also cause elevated blood ammonia. 3. Upper gastrointestinal bleeding: increased protein decomposition products are formed through the action of intestinal bacterial enzymes, and ammonia is absorbed into the blood via Intestinal mucosa absorption into the blood, can also make the blood ammonia elevated, elevated blood ammonia can induce hepatic encephalopathy.