Table 2.

Thiamine biomarkers used to measure recent intake and thiamine status

Biomarker	Specimen	Advantages	Disadvantages
Direct measurement
Thiamine	Plasma	Indicates recent intake	Not an indicator of thiamine status
ThMP	Plasma	Indicates recent intake	Not an indicator of thiamine status
ThDP	Whole blood; erythrocytes	Biologically active vitamer and indicator of thiamine status	Unstable if specimen is not properly handled
Indirect/functional measurement
ETK activity coefficient	Washed erythrocytes	Functional assay of biological activity	Assay is not readily available

ThMP, thiamine monophosphate; ThDP, thiamine diphosphate; ETK, erythrocyte transketolase.