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Erythrocyte transketolase activity coefficient (ETKAC) assay protocol for the assessment of thiamine status.

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Parkington, Damon A 
Cox, Lorna J 


Vitamin B1 (thiamine) is an essential nutrient that acts as a cofactor for a number of metabolic processes, particularly in energy metabolism. Symptoms of classic thiamine deficiency are recognized as beriberi, although clinical symptoms are nonspecific and recognition of subclinical deficiency is difficult. Therefore, reliable biomarkers of thiamine status are required. Thiamine diphosphate is a cofactor for transketolase, including erythrocyte transketolase (ETK). The ETK activity assay as an indirect, functional marker of thiamine status has been used for over 50 years. The ETK activity assay provides a sensitive and specific biomarker of thiamine status; however, there is a lack of consensus over the cutoffs for deficiency, partly due to a lack of assay harmonization. Here, we provide a step-by-step protocol for the measurement of ETK activity and the calculation of the ETK activity coefficient, including detailed explanations of equipment and chemicals required and guidance for quality control procedures. Harmonization of the protocol will provide the basis for the development of internationally recognized cutoffs for thiamine insufficiency. The establishment of quality control materials and a quality assurance scheme are recommended to provide reliability. This will ensure that the ETK activity assay remains an important method for the assessment of thiamine status.



ETKAC, beriberi, thiamine, vitamin B1, Beriberi, Biomarkers, Disease Management, Disease Susceptibility, Enzyme Activation, Enzyme Assays, Erythrocytes, Humans, Reproducibility of Results, Severity of Illness Index, Thiamine, Thiamine Deficiency, Transketolase

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Ann N Y Acad Sci

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Cambridge University Hospitals NHS Foundation Trust (CUH) (146281)
Bill & Melinda Gates Foundation (via Sackler Institute for Nutrition Science) (Unknown)
National Institute for Health and Care Research (IS-BRC-1215-20014)
KSJ, DAP and AK are supported by the National Institute for Health Research (NIHR) Cambridge Biomedical Research Centre (IS-BRC-1215- 20014). The NIHR Cambridge Biomedical Research Centre is a partnership between Cambridge University Hospitals NHS Foundation Trust and the University of Cambridge, funded by the NIHR. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. LJC has an advisory role at the NIHR BRC Nutritional Biomarker Laboratory.