Improvements to the [13C]MTG breath test for measuring fat digestion

Slater, Christine (2004) Improvements to the [13C]MTG breath test for measuring fat digestion. PhD thesis, University of Glasgow.

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Abstract

There is a need for a robust, non-invasive clinical test to assess fat digestion, especially in children with cystic fibrosis. Labelling of substrates with 13C enables investigation of their digestion, absorption and subsequent metabolism. The mixed triacylglcerol (MTG) 13C-breath test is an indirect measure of fat digestion, and therefore exocrine pancreatic function. Cystic fibrosis is the commonest cause of pancreatic insufficiency in children. 13C-breath tests are particularly attractive for use in children because they are non-invasive, and pose no radiation hazard. MTG is a synthetic triacylglycerol (1,3 distearyl 2-[1-13C] octanoyl-glycerol). Pancreatic lipases preferentially hydrolyse triacylglycerol at the sn-1 and -3 positions, releasing 13C-labelled octanoate which is rapidly absorbed and oxidised with the generation of 13CO2. Quantitation of tracer excretion requires knowledge of the volume of distribution of the 13C-labelled tracer as well as quantity of ingested dose and abundance in breath CO2. In 13C-breath tests, labelled CO2 originating from oxidation of the tracer is diluted by endogenously produced CO2 from metabolic processes. Therefore knowledge of CO2 production rate (VCO2) is required. A resting value based on basal metabolic rate is often assumed, but if subjects are not at rest and in the postprandial state throughout the test, this will be an underestimate of the true CO2 production rate and therefore underestimate the quantity of tracer excreted. The MTG breath test has not been widely adopted because it lacks discrimination due to its poor specificity. The hypothesis tested in this study is that the poor specificity of the [13C]MTG breath test is due to lack of knowledge of the true carbon dioxide production rate during the test. (Abstract shortened by ProQuest.).

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: Lawrence Weaver
Keywords: Medicine
Date of Award: 2004
Depositing User: Enlighten Team
Unique ID: glathesis:2004-71085
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 10 May 2019 10:49
Last Modified: 10 May 2019 10:49
URI: http://theses.gla.ac.uk/id/eprint/71085

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