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  A novel variant of the 13C-methacetin liver function breath test that eliminates the confounding effect of individual differences in sytemic CO2 kinetics

Holzhütter, H.-G., Wuensch, T., Gajowski, R., Berndt, N., Bulik, S., Meierhofer, D., et al. (2020). A novel variant of the 13C-methacetin liver function breath test that eliminates the confounding effect of individual differences in sytemic CO2 kinetics. Archives of Toxicology, 94(2), 401-415. doi:10.1007/s00204-020-02654-0.

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Holzhütter, Hermann-Georg, Author
Wuensch, Tilo, Author
Gajowski, Robert1, Author              
Berndt, Nikolaus, Author
Bulik, Sascha, Author
Meierhofer, David1, Author              
Stockmann, Martin, Author
1Mass Spectrometry (Head: David Meierhofer), Scientific Service (Head: Christoph Krukenkamp), Max Planck Institute for Molecular Genetics, Max Planck Society, ou_1479669              


Free keywords: 13C-methacetin; Breath test; 13CO2 kinetics; Liver function; Compartment model
 Abstract: The principle of dynamic liver function breath tests is founded on the administration of a 13C-labeled drug and subsequent monitoring of 13CO2 in the breath, quantified as time series delta over natural baseline 13CO2 (DOB) liberated from the drug during hepatic CYP-dependent detoxification. One confounding factor limiting the diagnostic value of such tests is that only a fraction of the liberated 13CO2 is immediately exhaled, while another fraction is taken up by body compartments from which it returns with delay to the plasma. The aims of this study were to establish a novel variant of the methacetin-based breath test LiMAx that allows to estimate and to eliminate the confounding effect of systemic 13CO2 distribution on the DOB curve and thus enables a more reliable assessment of the hepatic detoxification capacity compared with the conventional LiMAx test. We designed a new test variant (named "2DOB") consisting of two consecutive phases. Phase 1 is initiated by the intravenous administration of 13C-bicarbonate. Phase 2 starts about 30 min later with the intravenous administration of the 13C-labelled test drug. Using compartment modelling, the resulting 2-phasic DOB curve yields the rate constants for the irreversible elimination and the reversible exchange of plasma 13CO2 with body compartments (phase 1) and for the detoxification and exchange of the drug with body compartments (phase 2). We carried out the 2DOB test with the test drug 13C-methacetin in 16 subjects with chronic liver pathologies and 22 normal subjects, who also underwent the conventional LiMAx test. Individual differences in the systemic CO2 kinetics can lead to deviations up to a factor of 2 in the maximum of DOB curves (coefficient of variation CV ≈ 0.2) which, in particular, may hamper the discrimination between subjects with normal or mildly impaired detoxification capacities. The novel test revealed that a significant portion of the drug is not immediately metabolized, but transiently taken up into a storage compartment. Intriguingly, not only the hepatic detoxification rate but also the storage capacity of the drug, turned out to be indicative for a normal liver function. We thus used both parameters to define a scoring function which yielded an excellent disease classification (AUC = 0.95) and a high correlation with the MELD score (RSpearman = 0.92). The novel test variant 2DOB promises a significant improvement in the assessment of impaired hepatic detoxification capacity. The suitability of the test for the reliable characterization of the natural history of chronic liver diseases (fatty liver-fibrosis-cirrhosis) has to be assessed in further studies.


Language(s): eng - English
 Dates: 2020-01-272020-02-04
 Publication Status: Published online
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: -
 Identifiers: DOI: 10.1007/s00204-020-02654-0
 Degree: -



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Title: Archives of Toxicology
  Abbreviation : Arch. Toxicol.
Source Genre: Journal
Publ. Info: Springer Berlin Heidelberg
Pages: 15 Volume / Issue: 94 (2) Sequence Number: - Start / End Page: 401 - 415 Identifier: ISSN: 0340-5761
CoNE: https://pure.mpg.de/cone/journals/resource/0340-5761