18.3: Conclusions (20a.3)

Despite its long history and the well-established adverse effects of deficiency, thiamine lacks both a standardized biochemical biomarker and interpretative criteria. The most common biomarker currently in use is blood ThDP, likely due to the growing availability of HPLC-FLD and ease of standardization. However, the lack of clinically meaningful cut-offs limits the practical use of blood ThDP. Although ETKac is still measured in a few laboratories and has a well-established cut-off for deficiency, the lack of availability of the assay limits its use. At the individual level, use of a therapeutic thiamine challenge remains the clear course of action given the safety of thiamine, when compared to the known severe adverse outcomes of untreated thiamine deficiency. At the population level, challenges still exist. However, the growing interest and method development for thiamine assessment via dried blood spots is an exciting prospect. Use of dried blood spots could ease sample collection, processing, storage and shipment costs, thus extending the possibility of field- friendly assessments, such as integration into population-level surveys in beriberi-endemic regions. Such thiamine assessments would provide improved estimates of the global burden of thiamine deficiency and trigger appropriate action for public health interventions in necessary areas. Future research should continue exploring: 1) large-scale testing of dried blood spot samples and potentially also the development of a point-of-care thiamine assessment; 2) the development of interpretative criteria for whole blood ThDP; and 3) improved inter-laboratory and standardization of ETKac.