Curbside Consultation of the Liver: 49 Clinical Questions

Mitchell L. Shiffman, MD

Question 45: My Patient With Cirrhosis Has An Elevated Serum Ammonia But No Symptoms Of Hepatic Encephalopathy. How Much Lactulose Should I Recommend? (continued)

Paul Arnold, MD; Adil Habib, MD; Douglas M. Heuman, MD

We do not place much reliance on blood ammonia measurements in the clinical setting. Hepatic encephalopathy is not a biochemical diagnosis but a clinical diagnosis based on history and neuropsychological findings. Ammonia is not the only toxin contributing to encephalopathy; ambient levels of blood ammonia correlate poorly with severity of encephalopathy, and artefactual elevations of ammonia due to improper sample handling are very common. That having been said, cirrhotic patients may have subtle cognitive defects that can escape detection with routine clinical evaluation, and treatment of…