The Ongoing Debate of Serum Ammonia Levels in Cirrhosis: the Good, the Bad, and the Ugly

Serum ammonia testing in hepatic encephalopathy (HE) has been long debated in the field of hepatology. Although central to the pathophysiology of HE, serum ammonia testing is fraught with complexities that can lead to challenges in laboratory collection and interpretation. Although there is some disagreement across guideline organizations regarding routine testing of ammonia in HE, all acknowledge that normal values, although possible in HE, may warrant reconsideration of the diagnosis. In this study, we propose a nuanced approach to ammonia testing in HE. Serum ammonia testing provides little additional benefit in clinical scenarios with a high or low pretest probability for HE. However, if the pretest probability for HE is uncertain, a low ammonia level may reduce the posttest probability of HE. In this scenario, other etiologies of altered mental status should be explored. Future research should focus on developing a standardized approach to serum ammonia collection, processing, and interpretation.

Automated summary

The use of serum ammonia testing in hepatic encephalopathy (HE) has been controversial in the field of hepatology. Despite its importance in the pathophysiology of HE, the complexity of serum ammonia testing can pose challenges in laboratory collection and interpretation. This study proposes a nuanced approach to ammonia testing in HE, highlighting its limited clinical benefit in scenarios with high or low pretest probability for HE, but potential usefulness in uncertain cases. The development of standardized approaches to serum ammonia collection, processing, and interpretation should be a focus of future research.