Detecting Vitamin B1 (Thiamine) Deficiency

Appropriate Utilization of Vitamin B1 Testing in Whole Blood and Plasma

Vitamin B1 (Thiamine): Proper Use and Name Update

ARUP Laboratories has updated the name of our “Vitamin B1 Plasma” test to Vitamin B1 Supplementation Monitoring, Plasma. This change is designed to clarify the appropriate utilization for Vitamin B1 testing in plasma, which has limited clinical utility and should only be used to monitor vitamin B1 supplement ation.

To measure vitamin B1 sufficiency, whole blood testing (Vitamin B1 (Thiamine), Whole Blood) must be ordered.

Why Proper Utilization Matters

Vitamin B1 (thiamine) is essential for energy metabolism and neurological function. Accurate measurement is critical for diagnosing deficiencies that may lead to serious conditions, including permanent neurological damage, memory loss, and death. ARUP offers testing in both whole blood and plasma; however, whole blood testing should be used to evaluate deficiency.

  • Whole blood reflects body stores and is the appropriate method for assessing sufficiency.
  • Plasma testing has very limited clinical utility and should not be used to evaluate thiamine status.

Test Name and Code

Clinical Use

Vitamin B1 (Thiamine), Whole Blood (0080388)Use for the evaluation of thiamine sufficiency
Vitamin B1 Supplementation Monitoring, Plasma (0080389)Limited clinical use; only use to monitor supplementation

Frequently Asked Questions

How can I help ensure the correct test is ordered?

For the vast majority of patients, whole blood thiamine is the correct test. Consider these options to encourage proper test utilization:

  • Update the plasma test name in your ordering system to Vitamin B1 Supplementation Monitoring, Plasma.
  • Consider removing plasma entirely or restrict it to special request only.
When is plasma testing appropriate?

Very rarely. Plasma reflects recent intake only and does not indicate deficiency risk, which may lead to irreversible neurological damage or death.

How can I educate providers?

Share this webpage for quick reference or use the printable/email-ready education piece (download available here).

This test name update is meant to reduce confusion and differentiate plasma testing from whole blood testing

Note: Only the name has changed, all other components of the test remain the same.

Additional Resources