Produced by colonic bacteria and by deamination of dietary glutamine.
After intestinal absorption, NH3 is metabolized by the urea cycle in periportal hepatocytes and excreted via the kidneys and colon.
In cirrhosis portosystemic shunting and decline in hepatic urea synthesis causes an accumulation of NH3 in the blood, and increases levels in the CNS due to blood brain barrier disruption (Butterworth RF).
associated with urea cycle disorders.
The testing for ammonia is delicate and subject to spuriously elevations.
Levels rise with standing blood because of in vitro deaminization of amino acids.
Elevations s of ALt and GGT enzymes are independently known to produce false elevations in ammonia levels.