A comparison of the reproducibility of the parameters of the ¹³C-aminopyrine breath test for the assessment of hepatic function

Abstract

This study determined the within-subject and between-subject variability of different ways of expressing the results of the ¹³C-aminopyrine breath test (¹³C-ABT) and the effect of shortening the test duration. The ¹³C-ABT was conducted on three separate occasions in 10 healthy volunteers and on a single occasion in 22 patients with established liver cirrhosis. The within-subject variability of cumulative percentage dose recovered (cPDR), using measured CO₂ production rate (VCO₂), in the reference group over three trials was 15% over 120 min. Higher within-subject variability in cPDR would have been evident if the test was terminated at either 30 or 60 min. Substitution of predicted VCO₂ to calculate cPDR yielded comparable values at all time points. Significant differences between cirrhotics and reference group were evident after just 10 min using PDR/h, cPDR or enrichment (all P<0.05). The ABT demonstrates clinically acceptable reproducibility. Shortening of the duration may make the test more acceptable clinically, but it is associated with increasing imprecision.

Keywords:

• ¹³C-aminopyrine breath test
• liver function
• cirrhosis
• VCO₂ production
• intra-individual variability
• inter-individual variability
• isotope application in medicine
• human
• carbon-13

Acknowledgements

The authors thank Professor M. Elia and Dr J. Jackson for their advice and all the volunteers who took part in this study.