Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA154

Poster Communications

13C methacetin breath test for assessment of liver function: validation of a shortened collection time in healthy adults

G. H. Evans1, L. Bagley1, A. Yau1, L. Mattin1, V. McIver1, E. Pagani2, J. Stewart2, A. Tucker2

1. School of Healthcare Science, Manchester Metropolitan University, Manchester, United Kingdom. 2. Seahorse Laboratories, London, United Kingdom.

13C breath tests for clinical assessment of physiological function have received much recent attention due to their non-invasive nature and their relatively low cost. The 13C methacetin test assesses cytochrome P450 dependent liver function [1] and has been shown to accurately predict the degree of liver cirrhosis in chronic liver disease patients [2]. The traditional version of this test involves 120 minutes of breath sample collection, which may not always be practical in a clinical setting. However, Schneider et al. [3] have previously demonstrated that a shortened test with a single sample collection 15 minutes after ingestion may be sufficient for accurate assessment of liver function by 13C breath excretion. There is still, nevertheless, confusion over what cut-off values should be used to assess liver function at this time point. Consequently, the purpose of the current study was to assess liver function in healthy individuals and determine normal values at the 15-minute sample collection using the 13C methacetin test. Twenty six male and female adults completed this test. All were generally healthy, with no history of liver disease, as determined by a pre-participation medical screening questionnaire. Participants completed one experimental trial which involved arriving at the laboratory in a fasted state before drinking 100 mL of water with the addition of 75 mg of 13C methacetin. End expiratory breath samples were collected immediately prior to ingestion and 10, 15, 20, 30, 40, 50, 60, 80, 100 and 120 minutes after ingestion. Samples were analysed for 13CO2:12CO2 ratio using infrared spectroscopy. The difference between values from baseline is expressed as delta over baseline (DOB). The median cumulative dose excretion after 120 minutes was 26.0 %13C with an upper and lower 95% confidence interval of 27.0 and 23.2 %13C respectively. DOB data (Figure 1) demonstrated that peak values for 54% of participants occurred 15 minutes after ingestion and peak values for 88% of participants occurring within 20 minutes of ingestion. Median DOB at 15 minutes was 20.2 with upper and lower confidence intervals of 16.3 and 21.0 respectively. The results of this study demonstrate that, in this small cohort of healthy participants, obtaining a breath sample 15 minutes after ingestion of 13C methacetin is sufficient to provide an accurate assessment of liver function and that normal DOB values for this time point are likely to be between 16.3 and 21.0. This has potential clinical significance in reducing time and cost commitment for patients and healthcare providers, and merits further work to establish cut-off points for determination of liver function in clinical populations.

Where applicable, experiments conform with Society ethical requirements