Dive into the complexities of hepatic encephalopathy, a condition linked to liver dysfunction and characterized by confusion and cognitive decline. Discover why ammonia levels aren't reliable for diagnosis and the significance of clinical evaluation. Learn about the role of lactulose in treatment, which helps eliminate ammonia from the body while providing a laxative effect. The discussion also highlights the importance of ruling out other conditions when assessing neuropsychiatric symptoms in patients with cirrhosis.
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Ammonia Levels Are Unreliable For Diagnosis
Ammonia levels are neither sensitive nor specific for diagnosing hepatic encephalopathy.
Clinical diagnosis based on confusion, known cirrhosis, and excluding other causes is primary.
volunteer_activism ADVICE
Treat HE Based On Clinical Suspicion
Consider hepatic encephalopathy after excluding seizures, infection, and intracranial hemorrhage in a cirrhotic patient with confusion.
Treat based on clinical suspicion rather than waiting for an elevated ammonia level.
volunteer_activism ADVICE
Use Lactulose As First-Line Treatment
Give lactulose as first-line treatment for suspected hepatic encephalopathy.
Administer orally or rectally as needed because it acidifies the gut and acts as a laxative to reduce ammonia absorption.
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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
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