Measuring thiamine status in dried blood spots.

BACKGROUND

A reliable and robust method with minimum sample collection requirement for thiamine assay is needed in clinical and research settings.

METHODS

A simple and robust assay for three vitamers (thiamine, Th; thiamine monophosphate, TMP; and thiamine diphosphate, TDP) using a 6.35-mm dried blood spot (DBS) disc was developed, validated and applied.

RESULTS

We were able to quantify accurately thiamine status covering all major vitamers Th, TMP and TDP with acceptable recovery (90%-114%), limit of quantification (TDP: 3.0 nM, TMP and Th: 1.5 nM), linearity (TDP: LOQ 400 nM, TMP and Th: LOQ 50 nM, all R2 > 0.99), imprecision (coefficient variation < 4.3% for TDP, <10.0% for TMP and < 12.6% for Th) and stability at -20 °C for up to 42 days. By recruiting 20 healthy participants, we cross compared finger capillary DBS with venous whole blood and venous blood pre-spotted on filter papers. The results demonstrated minimum bias between methods. A preliminary dosing study showed the method had excellent sensitivity after a single dose of supplemental thiamine.

CONCLUSIONS

We have developed and clinically validated a simple, robust, accurate and sensitive assay for the analysis of thiamine status in DBS, suitable for large-scale population studies.