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Contributor: Alec Coston, MD Educational Pearls: Hepatic encephalopathy (HE) is defined as a disruption in brain function that results from impaired liver function or portosystemic shunting. Manifests as various neurologic and psychiatric symptoms such as confusion, inattention, and cognitive dysfunction Although ammonia levels have historically been recognized as important criteria for HE, the diagnosis is ultimately made clinically. An elevated ammonia level lacks sensitivity and specificity for HE Trends in ammonia levels do not correlate with disease improvement or resolution A 2020 study published in the American Journal of Gastroenterology evaluated 551 patients diagnosed with hepatic encephalopathy and treated with standard therapy Only 60% of patients had an elevated ammonia level, demonstrating the limitations of ammonia levels However, a normal ammonia level in a patient with concern for HE should raise suspicion for other pathology. In patients with cirrhosis presenting with neuropsychiatric symptoms, consider HE as the diagnosis after excluding other potential causes of altered mental status (i.e., Seizure, infection, intracranial hemorrhage) The primary treatment is lactulose Works by acidifying the gastrointestinal tract. Ammonia (NH₃) is converted into ammonium (NH₄⁺), which is poorly absorbed and subsequently eliminated from the body Also exerts a laxative effect, further enhancing elimination References: Haj M, Rockey DC. Ammonia Levels Do Not Guide Clinical Management of Patients With Hepatic Encephalopathy Caused by Cirrhosis. Am J Gastroenterol. 2020 May;115(5):723-728. doi: 10.14309/ajg.0000000000000343. PMID: 31658104.\ Lee F, Frederick RT. Hepatic Encephalopathy-A Guide to Laboratory Testing. Clin Liver Dis. 2024 May;28(2):225-236. doi: 10.1016/j.cld.2024.01.003. Epub 2024 Jan 30. PMID: 38548435. Vilstrup, Hendrik1; Amodio, Piero2; Bajaj, Jasmohan3,4; Cordoba, Juan1,5; Ferenci, Peter6; Mullen, Kevin D.7; Weissenborn, Karin8; Wong, Philip9. Hepatic encephalopathy in chronic liver disease: 2014 Practice Guideline by the American Association for the Study Of Liver Diseases and the European Association for the Study of the Liver. Hepatology 60(2):p 715-735, August 2014. | DOI: 10.1002/hep.27210 Weissenborn K. Hepatic Encephalopathy: Definition, Clinical Grading and Diagnostic Principles. Drugs. 2019 Feb;79(Suppl 1):5-9. doi: 10.1007/s40265-018-1018-z. PMID: 30706420; PMCID: PMC6416238. Summarized by Ashley Lyons, OMS3 | Edited by Ashley Lyons & Jorge Chalit, OMS4 Get your tickets to Tox Talks Event, Sept 11, 2025: https://emergencymedicalminute.org/events-2/ Donate: https://emergencymedicalminute.org/donate/