Jacoby KJ, et al. - By performing this retrospective observational analysis, researchers investigated the etiology as well as the results of critically ill patients experiencing severe hyperammonemia. Participants were adults (18 years or older) who got admission to a MICU from 2007 to 2016 and who exhibited a serum ammonia level > 180 μmol/L (3 times the upper limit of normal). Overall participants were 78, including 45 male and 32 female, with a median age of 52 years. The most common etiology for hyperammonemia development was an acute-on-chronic liver failure (49 %) or decompensated cirrhosis (27 %), and less commonly prior gastric bypass (9%), acute hepatic failure (6%), or valproic acid (3%) caused hyperammonemia. The median serum ammonia level was detected to be 201 μmol/L on admission, with a peak value of 245 μmol/L. During the hospital stay, the deaths of 50 (64%) patients were reported. Overall, findings revealed high mortality rate as well as the presence of the risk of developing cerebral edema among critically ill patients with severe hyperammonemia.