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Vitamins

Active Vitamin B12 Test

Active Vitamin B12 measures the bioavailable form of vitamin B12 that your body can readily use. Unlike total B12, this test may provide a more accurate picture of your actual B12 status and cellular availability.

Doctor's Assessment Included

Reference Ranges

See the value that applies to you:

Choose male or female — this range differs by sex.

Enter your age — this range changes with age.

This range also depends on context such as cycle phase or sample material; the highlighted rows apply to your group.

Male Your group
pmol/l
Low 35 Normal 108 High
Female Your group
pmol/l
Low 35 Normal 108 High

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

Check your own value

Active Vitamin B12: what this test measures

This test measures holotranscobalamin, the active fraction of vitamin B12 bound to transcobalamin II. This is the only form of B12 that can be taken up by all cells in your body for essential metabolic processes.

Active Vitamin B12: why this value matters

Vitamin B12 is considered essential for nerve function, red blood cell production, and DNA synthesis. Low active B12 levels may be associated with fatigue, neurological symptoms, and anaemia. Early detection could help healthcare providers intervene before symptoms progress.

Active Vitamin B12: when is testing worthwhile?

Testing may be recommended if you follow a vegetarian or vegan diet, experience unexplained fatigue or tingling in your extremities, are over 50, or have digestive conditions that could affect nutrient absorption. Consult your healthcare provider for guidance.

Active Vitamin B12: symptoms of a high or low value

Low Levels

Some people with low active B12 levels may experience fatigue, weakness, tingling or numbness in hands and feet, difficulty concentrating, mood changes, and pale skin. A healthcare provider should evaluate persistent symptoms.

High Levels

Elevated active B12 levels are less commonly associated with symptoms but may sometimes indicate underlying conditions such as liver disease or certain blood disorders. Your healthcare provider can help interpret high results in context.

Active Vitamin B12: lifestyle and this value

Including B12-rich foods such as meat, fish, eggs, and dairy in your diet may help support healthy levels. Those on plant-based diets might consider discussing supplementation with their healthcare provider. Regular monitoring can help track your status over time.

Active Vitamin B12: frequently asked questions

What is the difference between active B12 and total B12?

Active B12 measures only the form your cells can use, while total B12 includes both active and inactive forms. Active B12 is generally considered a more reliable early indicator of deficiency by many healthcare professionals.

Who may be at risk for low active B12?

People following vegan or vegetarian diets, older adults, those with digestive conditions like Crohn's disease or celiac disease, and individuals taking certain medications such as metformin or proton pump inhibitors may have an increased risk.

How often should I test my active B12 levels?

Testing frequency depends on your individual circumstances. Your healthcare provider can recommend an appropriate schedule based on your diet, medical history, and any symptoms you may be experiencing.

Tests with related values

These panels measure values from the same category as this marker.

General checkup

General checkup

A broad blood test covering 18 values across liver, kidneys, thyroid, heart, vitamins and blood count.

ALT (Alanine Aminotransferase) GGT (Gamma-Glutamyl Transferase) Creatinine eGFR (Estimated Glomerular Filtration Rate) TSH (Thyroid Stimulating Hormone) Total Cholesterol HDL Cholesterol LDL Cholesterol Triglycerides Glucose (Fasting) Vitamin D (25-OH) Vitamin B12 Ferritin Hemoglobin Leukocytes (WBC) Platelets (Thrombocytes) CRP (C-Reactive Protein) MCV (Mean Corpuscular Volume)
€199,-

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Medical standards

Dr. Naimi oversees the medical standards behind our content and assessments.

Medical policy
CIBG Ministerie van Volksgezondheid,
Welzijn en Sport Official BIG registration BIG 49928676701 Opens in a new tab

Active Vitamin B12

€127,-