Serum ammonia does not guide management and is over utilised in patients with cirrhosis in hospital settings

Link to article at PubMed

Intern Med J. 2023 Mar 9. doi: 10.1111/imj.16053. Online ahead of print.


BACKGROUND AND AIM: Hepatic encephalopathy is a confusional state associated with cirrhosis. Serum ammonia levels are neither sensitive nor specific for the diagnosis. We audited the ordering location and hospital unit whilst assessing the impact on management at a major Australian tertiary centre.

METHODS: We conducted a single centre retrospective chart review of ordering of serum ammonia levels between 1/03/2019-29/02/2020 at The Royal Melbourne Hospital, a tertiary referral centre in Melbourne, Victoria. Demographic, medication, pathology results including serum ammonia measurements were collected. The main outcomes assessed: Ordering location, sensitivity, specificity and impact on management.

RESULTS: 1007 serum ammonia tests were ordered in 425 patients. Nearly all ammonia ordering was by non-Gastroenterologists; 24.2% by the intensive care unit (ICU), 23.1% by general medicine and 19.5% by the emergency department (ED). Only 21.6% of patients had a history of cirrhosis with hepatic encephalopathy diagnosed in 13.6%. On subgroup analysis 217 ammonia tests were performed in 92 patients with cirrhosis. Cirrhotic patients were older (64 versus 59 years, p=0.012) and had higher median ammonia levels (64.46 μmol/L versus 59 μmol/L, p < 0.001) compared to non-cirrhotic patients. In cirrhotic patients the sensitivity and specificity for serum ammonia and diagnosis of hepatic encephalopathy was 75% and 52.3% respectively.

CONCLUSION: We affirm the poor utility of serum ammonia levels for guiding management of hepatic encephalopathy within the Australian context. ED and general medical units account for the majority of test ordering within the hospital. Understanding where ordering occurs provides a target for targeted education. This article is protected by copyright. All rights reserved.

PMID:36891668 | DOI:10.1111/imj.16053

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