Measurement of gastric emptying using a C-13-octanoic acid breath test with Wagner-Nelson analysis and scintigraphy in type 2 diabetes.
Date
2022
Authors
Trahair, L.G.
Nauck, M.A.
Wu, T.
Stevens, J.E.
Buttfield, M.D.
Hatzinikolas, S.
Pham, H.
Meier, J.J.
Rayner, C.K.
Horowitz, M.L.
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Journal article
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Internal Medicine Journal, 2022; 52(S2):54-55
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G. Trahair, M. A. Nauck, T. Wu, J. E. Stevens, M. D. Buttfield, S Hatzinikolas, H. Pham, J. J. Meier, C. K. Rayner, M. Horowitz, K. Jones
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Abstract
Background: Breath tests utilising 13C-labelled substrates have been applied widely for the assessment of gastric emptying. A limitation of conventional breath test modelling is that the results should be regarded as notional, rather than precise. Wagner- Nelson analysis is a pharmacokinetic model that can be utilised to generate a gastric emptying curve from the % ¹³CO₂ measured in breath samples. Aims: To compare Wagner-Nelson analysis with (i) scintigraphy and (ii) conventional breath test modelling to quantify gastric emptying in type 2 diabetes. Methods: Thirteen subjects with type 2 diabetes (age 68.1±1.5 years, body mass index 31.0±0.9kg/m², glycated haemoglobin (HbA1c) 6.3±0.2%) consumed a mashed potato meal comprising 65g powdered potato, 20g glucose, 250ml water, an egg yolk labelled with 100μL 13Coctanoic acid and 20MBq 99mTc-calcium phytate. Scintigraphic data were acquired and breath samples collected for 4 hours after the meal. Gastric emptying curves were derived based on each technique; the 50% emptying time and intragastric retention at 60min were also calculated. Results: With Wagner-Nelson analysis, a Kel=0.60 (the elimination constant) best approximated the scintigraphic gastric emptying curve. There was a relationship between the T50 calculated with scintigraphy and that by both Wagner-Nelson Kel=0.60 (r²=0.45, P<0.05) and conventional analysis (r²=0.44, P<0.05). There was no significant difference in the 50% gastric emptying time measured by scintigraphy (68.5±4.8 min) and Wagner-Nelson Kel=0.60 (71.3±4.5 min), however, the gastric emptying time calculated by conventional analysis was much greater at 164.7±6.0 min (P<0.001). Conclusion: In type 2 diabetes, gastric emptying of a mashed potato meal measured using a ¹³C-octanoic acid breath test analysed with Wagner-Nelson Kel=0.60 closely reflects measurements obtained with scintigraphy, whereas, in absolute terms, the conventional breath test analysis does not.
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© 2022 Royal Australasian College of Physicians. Copyright of individual abstracts remains with the authors.