Protocol and application of basal erythrocyte transketolase activity to improve assessment of thiamine status.
Annals of the New York Academy of Sciences 2023
DOI : 10.1111/nyas.14962
PubMed ID : 36719404
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.
Thiamine (vitamin B1) is an essential nutrient required for many metabolic processes, including carbohydrate metabolism. Measures of thiamine in the body (biomarkers) are required because (1) clinical symptoms of acute deficiency, leading to beriberi, are poorly defined, and (2) to identify sub-clinical thiamine deficiency. We expect that sub-clinical thiamine deficiency has detrimental effects on child development, but we still do not know how common this problem is.
Different methods have been used to measure thiamine status and there is little consensus on the interpretation of the data. In order to help improve the consistency of measurement of thiamine, we provide in this manuscript a clear protocol for the measurement of transketolase activity, a thiamine-dependent enzyme found in red blood cells (erythrocytes) – so called erythrocyte transketolase activity. We demonstrate the use of this method in samples from women of reproductive age who took part in the UK National Diet and Nutrition Survey and from participants in the ‘Keneba Biobank’, a biospecimen repository from The Gambia. We demonstrate much higher levels of thiamine deficiency in Gambian compared with UK women.
The publication of a standard protocol for measuring erythrocyte transketolase activity allows other laboratories to confidently set up the method in their own laboratory. This will improve replication between laboratories and allow harmonization of results between laboratories and studies. In turn, this will allow data from different studies to be combined and help lead to improvements in our understanding of thiamine deficiency, its causes and its consequences.