Ammonia: more than a neurotoxin?

Ammonia is an inorganic nitrogen compound that is metabolized and produced in all tissues via a number of important biochemical reactions. However, a major source of ammonia generation occurs in the gut following protein digestion and amino acid deamination. The subsequent ammonia-rich portal blood is effectively removed by the urea cycle in a healthy liver, maintaining circulating concentrations of ammonia within 35–65 μM. When liver function is compromized, hyperammonaemia arises delivering toxic concentrations of ammonia to the brain, causing deleterious effects.