Insight into your vitamin B12 level.
Vitamin B12 (cobalamin) plays a role in the production of red blood cells and the functioning of the nervous system. A test gives insight into your B12 level, with personal explanation from our doctors.
Also known as: cobalamin, active B12, holoTC
Personal assessment by our BIG-registered Bloodworks® doctors
By the Bloodworks editorial team
Vitamin B12 blood test
- Total
- 59,-
Next step: choose your collection point
- No referral needed
- 1000+ collection points
- Results typically within 2 working days
- Every result reviewed by a BIG-registered doctor
For a complete B vitamin picture
Combine with Folic Acid and Homocysteine
For a more complete picture, combine B12 with folic acid (B11/B9) and homocysteine, together these give the most comprehensive B vitamin overview.
View Vitamins & Minerals package · 159,-How Bloodworks works
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Background
What is vitamin B12?
Vitamin B12 (cobalamin) is a water-soluble vitamin needed by the body for the production of red blood cells, the functioning of the nervous system, and DNA synthesis. B12 is found almost exclusively in animal products such as meat, fish, eggs, and dairy.
B12 is absorbed in the stomach with the help of a protein called intrinsic factor. People following a vegetarian or vegan diet, older adults, people with gastrointestinal conditions, or those who have had gastric surgery have an increased risk of a lower B12 status. The standard measurement of total B12 gives an initial picture; for borderline values or suspected functional deficiency, additional testing (such as Holo-TC, MMA, or homocysteine) may be worthwhile.
In brief
Cobalamin
Water-soluble B vitamin
Animal sources
Meat, fish, eggs, dairy
Gastric absorption
Requires intrinsic factor
Blood & nerve
Essential for both
This marker is also included in
Testing several values in a single draw takes one blood collection and gives a more complete picture. The choice is yours.
Common reasons to test
When can insight into your Vitamin B12 be valuable?
Below are some situations in which measuring Vitamin B12 can provide insight.
With persistent fatigue or difficulty concentrating
These complaints are general and can have many causes; a low B12 level can be one of the factors. A test gives a starting point.
With tingling or numbness
Tingling or numbness in the hands or feet can fit with a longer-standing deficiency. With these complaints in particular, the result deserves attention.
With a vegetarian or vegan diet
Vitamin B12 is found almost exclusively in animal products. Those who eat plant-based rely on fortified products or supplementation; a test shows where you stand.
When using stomach acid reducers or metformin
Long-term use of stomach acid reducers or metformin can reduce the absorption of B12. Your prescribing doctor remains in charge; a test gives insight into your level.
After gastric surgery or with bowel conditions
After stomach surgery and with bowel conditions that limit absorption, B12 status can decline. A test shows whether the level is holding up.
At an older age
The absorption of B12 from food decreases with age; a test gives insight into whether the level is sufficient.
What your result means
Vitamin B12 too low or too high: what does your result mean?
Vitamin B12 is measured in picomoles per litre (pmol/L). Interpretation of your value is carried out against the standard reference ranges. For borderline cases or specific questions, additional testing can provide more information. Reference ranges also differ between laboratories and measurement methods; the ranges reported by the laboratory that performs your test are the ones that apply.
A low value
A low B12 level indicates a deficiency. Possible causes include a diet low in animal products, reduced absorption from the gut, or certain medications. Supplementation through diet, supplements, or (for absorption problems) injections is a common approach.
A normal value
B12 within the reference range gives a reassuring picture. For borderline values, especially at the lower end, additional testing (Holo-TC or homocysteine) can clarify whether a functional deficiency is present.
A high value
An elevated B12 level is often seen with active supplementation and is usually not harmful, excess B12 is excreted in the urine. For significantly elevated values without supplementation, our doctor provides explanation and context.
How we interpret your result
Our doctors interpret your B12 against the reference ranges of the laboratory and your personal context. You receive a report in plain language, as a starting point for your own insight or a conversation with your healthcare provider.
Related tests
Often combined with Vitamin B12.
A single marker gives one perspective. For a broader picture you can combine Vitamin B12 with a theme package or related markers.
+ 29,- blood draw fee per orderFree from 225,-
Frequently asked questions
Everything you want to know
Do I need to fast for a B12 test?
No, you do not need to fast for a B12 measurement.
What is the difference between total B12 and Holo-TC?
Total B12 measures all B12 in the blood. Holo-TC (active B12) measures only the portion that is biologically available to the cells. For borderline cases or suspected functional deficiency, Holo-TC can provide additional information.
How long should I stop taking B12 supplements for a reliable measurement?
For a baseline measurement, it is sometimes recommended to stop supplementation for 2 to 4 weeks. For active B12 injections, a longer waiting period is often advised. You may wish to discuss this with our doctor via customer service.
Which foods contain a lot of B12?
B12 is found mainly in meat, fish, eggs, and dairy. Plant-based foods contain virtually no B12, fortified plant-based milk alternatives and supplements are therefore an important source on a plant-based diet.
How often should I measure B12?
A single measurement is sufficient for initial insight. With active supplementation or as follow-up to a low baseline, re-testing after 3 to 6 months is common.
What is the difference with homocysteine?
Homocysteine is an amino acid that the body breaks down with the help of B12, B6, and folic acid. With a functional B12 deficiency, homocysteine can be elevated even when the B12 blood level still falls within the reference range.
What do I do with my result?
You will receive a PDF report with your value and explanation. What you do with it, such as discussing it with your GP, adjusting your diet, or taking no action, remains entirely your choice.
Can I share my report with my GP?
Yes, the report is written in medical language and contains all relevant laboratory information.
What does vitamin B12 do in the body?
Vitamin B12 is needed for the production of red blood cells, the functioning of the nervous system, and cell division. The body cannot make B12 itself and obtains it from food, almost exclusively from animal products. The liver keeps a reserve, which is why a deficiency often develops only gradually.
Which complaints can fit with a B12 deficiency?
Commonly reported complaints are fatigue, difficulty concentrating, dizziness, pallor, and tingling or numbness in the hands or feet. These complaints are general and can also have another cause, so on their own they say little. A test shows whether your B12 level could be one of the factors.
I eat plant-based: should I test my B12 or simply take a supplement?
Testing gives a starting point: you see where you stand and can compare the effect of supplementation later. Our doctor provides explanation and context with your result.
Can I have too much vitamin B12?
A high B12 level is common with supplement use and is usually harmless; excess B12 leaves the body through the urine. Our doctor provides explanation and context with your report.
Why can a B12 result be difficult to interpret?
The standard test measures the total amount of B12 in the blood, but that total value does not say everything about how much is actually available to the cells. A value within the reference range therefore does not always rule out a functional deficiency, and vice versa. That is why our doctor also weighs your complaints and situation in the explanation.
When should I take my result to my GP?
Neurological complaints such as persistent tingling or numbness always warrant a conversation with your GP, regardless of the result. The GP is also the right next step for an abnormal value without a clear explanation, or when complaints persist.
In the Health Guide
Read more about this value
Where do you give blood?
You can give blood at collection points across the Netherlands, usually without an appointment.
Find a collection point near you or read how a blood draw works.
Want to test multiple markers at once?
Combine Vitamin B12 with other markers via Bloodworks Select. The blood draw and collection fee is charged once per order, and is waived from 225,-.
Ready for insight into your vitamin B12 status?
You receive your B12 level including personal explanation from a doctor, typically within 2 working days. No referral required.