Nutritional Biomarker Laboratory, MRC Epidemiology Unit, University of Cambridge, Cambridge, UK.
Micronutrient Forum, Washington, District of Columbia, USA.
Ann N Y Acad Sci. 2023 Mar;1521(1):104-111. doi: 10.1111/nyas.14962. Epub 2023 Jan 31.
Thiamine (vitamin B1) is an essential micronutrient required as a cofactor in many metabolic processes. Clinical symptoms of thiamine deficiency are poorly defined, hence biomarkers of thiamine status are important. The erythrocyte transketolase activity coefficient (ETKac) is a sensitive measure of thiamine status, but its interpretation may be confounded where the availability of the transketolase enzyme is limited. Basal ETK activity per gram of hemoglobin provides a complementary biomarker of thiamine status; however, its measurement and calculation are poorly described. Here, we describe in detail the assessment of basal ETK activity, including the calculation of path length in microplates and the molar absorption coefficient of NADH specific to the assay, and the measurement of hemoglobin in sample hemolysates. To illustrate the application of the methods, we present ETKac and basal ETK activity from women in The Gambia and UK. In conclusion, we present a clear protocol for the measurement of basal ETK activity that will permit the harmonization of methods to improve replication between laboratories.
硫胺素（维生素 B1）是一种必需的微量营养素，作为许多代谢过程中的辅助因子。硫胺素缺乏的临床症状定义不明确，因此硫胺素状况的生物标志物很重要。红细胞转酮醇酶活性系数（ETKac）是硫胺素状况的敏感衡量指标，但在转酮醇酶的可用性受到限制的情况下，其解释可能会受到干扰。每克血红蛋白的基础 ETK 活性提供了硫胺素状况的另一种补充生物标志物；然而，其测量和计算方法描述得很差。在这里，我们详细描述了基础 ETK 活性的评估，包括微孔板中路径长度的计算和特定于测定的 NADH 的毫摩尔吸光系数，以及样品溶血物中血红蛋白的测量。为了说明该方法的应用，我们展示了冈比亚和英国女性的 ETKac 和基础 ETK 活性。总之，我们提出了一种明确的基础 ETK 活性测量方案，这将允许方法的协调，以提高实验室之间的复制性。
