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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.

Turnaround 24 hours, estimate Turnaround: up to 24 hours after your blood draw (estimate).

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 values can vary between laboratories. Discuss your results with your GP for explanation and treatment decisions.

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: how the blood test works

Referral
No GP referral needed. After the order we arrange the referral through ZorgDomein, within one business day; orders after 17:00 or at the weekend start on the next business day. ZorgDomein emails a barcode, and that barcode is what the draw site needs.
The draw
A blood draw from a vein in the arm, at a partner laboratory's draw site. No home kit, no finger prick.
Results
Turnaround: up to 24 hours after your blood draw (estimate).
Which test
Vitamin test · €149,-
Where
650+ draw sites run by independent laboratories across the Netherlands. Draw sites

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.

Test Products

This marker is included in the following test panels.

Results without a doctor's assessment

You receive your values with the unit and reference range. A doctor's assessment is not part of this site. Discuss your results with your GP for explanation and treatment decisions.

Active Vitamin B12

€127,-