SerumThiamin

Serum thiamin, or serumThiamin, is the concentration of the vitamin thiamine (vitamin B1) in blood serum. Thiamine is an essential water-soluble nutrient that serves as a cofactor for several enzymes involved in carbohydrate metabolism and energy production, including enzymes in the pyruvate dehydrogenase and transketolase reactions.

Measurement of serum thiamin is performed in some clinical and research settings using methods such as high-performance liquid chromatography (HPLC) with fluorescence detection after derivatization to thiochrome, or via liquid chromatography–mass spectrometry (LC-MS/MS). Results are typically reported in nanomoles per liter (nmol/L) or nanograms per milliliter, but reference ranges vary by assay and population, and there is no universal cutoff for deficiency.

Interpretation of serum thiamin has limitations. Serum levels primarily reflect recent intake and can fluctuate with meals, supplementation, hydration status, renal function, and inflammation. Consequently, a low serum thiamin does not definitively indicate tissue deficiency, and a normal level does not guarantee adequate body stores. For this reason, serum thiamin is often interpreted in the context of other indicators of thiamin status.

Clinical utility and relationships to other tests: In routine practice, more reliable indicators of thiamin status include erythrocyte thiamin diphosphate (TDP) concentrations and measures of erythrocyte transketolase activity. Serum thiamin may still be used in certain clinical scenarios or research to complement other assessments, but its results should be considered alongside additional biomarkers.

See also: thiamine deficiency, Wernicke-Korsakoff syndrome, nutrition assessment.