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Updated: Jan 4, 2026

Fast and Accurate Exhaled Breath Ammonia Measurement
Published on: June 11, 2014
Low-Value Levels: Ammonia Testing Does Not Improve the Outcomes of Overt Hepatic Encephalopathy
Elliot B Tapper1,2, Robert S Rahimi3
1Division of Gastroenterology and Hepatology, University of Michigan, Ann Arbor, Michigan, USA.
Hepatic encephalopathy is a clinical diagnosis. However, many clinicians measure ammonia levels in hospitalized patients presenting with hepatic encephalopathy. In this editorial, we review the results of an important study by Haj and Rockey. The authors examined the management decisions effected affected by and outcomes associated with (i) ordering an ammonia level and (ii) knowing the ammonia level. They found that ammonia level determination did not impact affect clinical decision-making or patient outcomes. These persuasive data demonstrate the limited clinical utility of ammonia levels and highlight the need for testing stewardship to dissuade unnecessary use through educational efforts and decision supports.
Hepatic encephalopathy is a clinical diagnosis. However, many clinicians measure ammonia levels in hospitalized patients presenting with hepatic encephalopathy. In this editorial, we review the results of an important study by Haj and Rockey. The authors examined the management decisions effected affected by and outcomes associated with (i) ordering an ammonia level and (ii) knowing the ammonia level. They found that ammonia level determination did not impact affect clinical decision-making or patient outcomes. These persuasive data demonstrate the limited clinical utility of ammonia levels and highlight the need for testing stewardship to dissuade unnecessary use through educational efforts and decision supports.
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