NIHR BRC Nutritional Biomarker Laboratory, MRC Epidemiology Unit, University of Cambridge, Cambridge, UK.
MRC Elsie Widdowson Laboratory, Cambridge, UK.
Ann N Y Acad Sci. 2021 Aug;1498(1):77-84. doi: 10.1111/nyas.14547. Epub 2020 Dec 22.
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.
维生素 B1（硫胺素）是一种必需的营养物质，作为许多代谢过程的辅助因子，特别是在能量代谢中。经典的硫胺素缺乏症的症状被认为是脚气病，尽管临床症状是非特异性的，并且识别亚临床缺乏症很困难。因此，需要可靠的硫胺素状态生物标志物。二磷酸硫胺素是转酮醇酶（包括红细胞转酮醇酶（ETK））的辅助因子。ETK 活性测定作为硫胺素状态的间接、功能性标志物已经使用了 50 多年。ETK 活性测定提供了一种敏感和特异性的硫胺素状态生物标志物；然而，由于缺乏测定方法的一致性，对于缺乏的切点缺乏共识，部分原因是缺乏测定方法的协调。在这里，我们提供了一种测量 ETK 活性和计算 ETK 活性系数的分步方案，包括对所需设备和化学品的详细解释，以及对质量控制程序的指导。该方案的协调将为制定国际公认的硫胺素不足切点提供基础。建议建立质量控制材料和质量保证计划以提供可靠性。这将确保 ETK 活性测定仍然是评估硫胺素状态的重要方法。
