Volumetric absorptive microsampling (VAMS) as a reliable tool to assess thiamine status in dried blood microsamples: a comparative study

Background: Although populations from low- and middle-income countries are at higher risk for thiamine (vitamin B-1) deficiency. accurate data on the global prevalence of thiamine deficiency are still lacking due to the difficult blood collection in remote regions. Volumetric absorptive microsampling (VAMS) from finger prick blood, generating dried blood microsamples, could simplify blood collection and allow the setup of epidemiological studies to improve the diagnosis. treatment, and prevention of thiamine deficiency. Objectives: To explore the potential of VAMS to serve as an alternative, patient-centric sampling strategy to evaluate the thiamine status. Methods: Venous liquid, venous VAMS, and capillary VAMS samples were collected from 50 healthy volunteers to compare thiamine diphosphate results, as a marker of thiamine (vitamin B1) status, in the different sample types. In addition, capillary VAMS samples were sent through regular mail to evaluate the influence of noncontrolled transport on the final results. All samples were analyzed using previously described fully validated LC-MS/MS methods. Results: A good agreement (94-100% of the results lying within 20% of their mean) was obtained for all comparisons: venous VAMS compared with venous liquid blood samples, capillary VAMS compared with venous VAMS samples. and capillary VAMS compared with venous liquid blood samples, with no significant bias (maximum mean bias of -1.0%; 95% CI: -4.1%. 2.0%) observed between the different methods. Finally, we demonstrated that VAMS samples can be safely transported through regular mail without affecting the final results. Conclusions: VAMS sampling can be used as a reliable alternative tool to evaluate the thiamine status, starting from only one drop of finger prick blood, in both developed and developing countries.