Vitamin B1, Plasma

Cleveland Heartlab Test, V

CPT Code: 84425
Order Code: C2491
ABN Requirement: No
Synonyms: Thiamine
Specimen: EDTA Plasma
Volume:  3.0 mL
Minimum Volume:  0.2 mL
Container: EDTA (Lavender Top) tube


EDTA Plasma

  1. Draw and gently invert 8 to 10 times.
  2. Centrifuge for 10 minutes.
  3. Pre-squeeze transfer pipet bulb and draw off approximately 2/3 of the upper plasma layer.
    Note: This ensures that the buffy coat and red cells remain undisturbed.
  4. Aliquot plasma into labeled transport tube and cap tightly. Discard original tube.
  5. Store transport tube refrigerated at 2-8°C until ready to ship.

Special Information: Aliquot plasma into tube and refrigerate within 1 hour of collection. Separate specimens must be submitted when multiple tests are ordered. Protect sample from light. This test is New York DOH approved.

Transport: Store EDTA Plasma at 2-8°C after collection and ship the same day per packaging instructions provided with the Cleveland HeartLab shipping box.


Ambient (15-25°C): Not Acceptable
Refrigerated (2-8°C):
7 days
Frozen (-20°C):
6 months
Deep Frozen (-70°C):
6 months

Causes for Rejection: Specimens other than EDTA plasma; hemolyzed specimens; specimens not protected from light; improper labeling; samples not stored properly; samples older than stability limits

Methodology: High Performance Liquid Chromatography (HPLC)

Turn Around Time: 4-7 days

Reference Range:

All Ages4-15

Clinical Significance: Thiamine (vitamin B1) is reported. However, thiamine diphosphate (TDP), the biologically active form of thiamine, is not found in measurable concentration in plasma, and is best determined in whole blood specimens. Plasma thiamine concentration reflects recent intake rather than body stores. Whole blood is the preferred specimen for thiamine assessment. Approximately 80% of thiamine present in whole blood is found in red blood cells.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.