Most ammonia is produced in the intestine by colonic breakdown of nitrogenous compounds and enterocytic catabolism of amino acids. Other sources of
ammonia are the kidneys and skeletal muscle. Normally,
ammonia is metabolized in the liver and promptly excreted through the kidneys or colon. Formation of glutamine from glutamate, by glutamine synthetase, in the liver and brain is another means of detoxifying ammonia.