Vitamin B1
Label Mnemonic: VTB1B
Epic code: LAB125
Downtime form: A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery
Commercial Mail-out Laboratory
5231 RCP
Whole Blood
Collection Medium:
Green top tube 4 mL (Na Heparin)
Preferred Minimum: 3 mL whole blood from green top (NA Heparin) tube.
Absolute Minimum: 0.6 mL whole blood from green top (NA Heparin) tube.
Rejection Criteria:
Any specimen other than whole blood. Plasma separator tubes. Glass tubes. Clotted or non-frozen specimens.
Delivery Instructions:
Deliver to laboratory immediately after collection. Critical frozen. Separate specimens must be submitted when multiple tests are ordered.
Turn Around Time:
2-4 days upon receipt at reference laboratory
Reference Range:
70-180 nmol/L
Interpretive Data:
This assay measures the concentration of thiamine diphosphate (TDP), the primary active form of vitamin B1. Approximately 90 percent of vitamin B1 present in whole blood is TDP. Thiamine and thiamine monophosphate, which comprise the remaining 10 percent, are not measured.
Whole blood is the preferred specimen for thiamine assessment. Approximately 80 percent of thiamine present in whole blood is found in red blood cells.

Do not use to monitor thiamine supplementation. Use to determine thiamine deficiency.
Quantitative High Performance Liquid Chromatography
CPT Code:
See Additional Information:
Specimens Requiring Immediate Delivery