What is the Vitamin B1 (Thiamine) test?

The Vitamin B1 (Thiamine) test measures the level of thiamine in the blood, an essential water-soluble vitamin required for carbohydrate metabolism and energy production. Thiamine plays a key role in converting glucose into energy and supporting normal nerve and muscle function.

Because the body stores very little thiamine, deficiency can develop quickly, particularly in people with poor dietary intake, chronic illness, or increased metabolic demand. Blood testing provides a reliable way to assess thiamine status when deficiency is suspected.

Clinically, this test is used to investigate unexplained fatigue, neurological symptoms, heart problems, and conditions associated with malnutrition or impaired absorption.

Why do I need a test for Vitamin B1 (Thiamine)?

Vitamin B1 deficiency can have serious neurological and cardiovascular consequences if not identified early. It is more common in individuals with high alcohol intake, malabsorption disorders, chronic illness, or those following very restricted diets.

Symptoms are often non-specific in early stages, which means deficiency can go undiagnosed. Testing allows accurate identification and timely intervention before severe complications develop.

You may need a Vitamin B1 test if you experience:

• Persistent fatigue or low energy
• Memory problems or confusion
• Tingling or numbness in hands and feet
• Muscle weakness
• Shortness of breath or heart-related symptoms
• Poor appetite or unexplained weight loss
• History of alcohol excess or malnutrition

Benefits of the Vitamin B1 (Thiamine) test

1. Detects thiamine deficiency early
   Identifies low levels before neurological or cardiac damage occurs.
2. Supports investigation of fatigue
   Helps determine whether low energy is related to impaired energy metabolism.
3. Assesses neurological health
   Useful when evaluating nerve symptoms or cognitive changes.
4. Supports cardiovascular assessment
   Thiamine deficiency can impair heart function if untreated.
5. Relevant for high-risk groups
   Important for individuals with alcohol dependence or malabsorption.
6. Guides appropriate supplementation
   Ensures thiamine replacement is evidence-based.
7. Helps prevent severe deficiency syndromes
   Reduces risk of conditions such as beriberi or Wernicke’s encephalopathy.
8. Improves diagnostic accuracy
   Provides objective biochemical confirmation.

Step-by-step – How we offer this test

Option 1: Clinic-based blood test (UK-wide)

• Choose your nearest UK clinic
• Attend your appointment
• A clinician draws a blood sample
• Results are processed and reported

Option 2: Home or hotel visit (+£60, UK-wide)

• A qualified phlebotomist visits your location
• Blood sample taken at home or in your hotel
• No need to travel or wait
• Results processed identically to clinic testing

Your results explained

Low Vitamin B1 (Thiamine) levels

Low thiamine levels indicate deficiency, which can impair energy metabolism and damage the nervous and cardiovascular systems.

UK reference range (low):

• < 70 nmol/L

Low levels are associated with fatigue, neuropathy, confusion, and in severe cases, cardiac complications.

Normal Vitamin B1 (Thiamine) levels

Normal levels suggest adequate thiamine availability for energy production and nerve function.

UK reference range (normal):

• 70 – 180 nmol/L

Symptoms within this range are unlikely to be caused by thiamine deficiency.

High Vitamin B1 (Thiamine) levels

High thiamine levels are uncommon and usually related to supplementation. Excess thiamine is generally excreted in urine.

UK reference range (high):

• > 180 nmol/L

High levels are rarely associated with toxicity.