Vitamin B12 test: measure your B12 level

Vitamin B12 is involved in your energy, the working of your nervous system, and the production of red blood cells. A deficiency often develops gradually, so symptoms such as fatigue may be attributed to other causes for a long time.

This test gives you a concrete data point that can help put vague symptoms into context. It is not a diagnosis, but a starting point for a conversation with your doctor.

This test can be of interest if you:

• eat a vegetarian or vegan diet, as plant-based food contains little B12
• are getting older, since B12 absorption can decline with age
• take certain medication that may affect absorption
• feel persistently tired or experience tingling

A deficiency is more common in vegetarians, vegans, older adults, and people on certain medication. If you recognise yourself here, a measurement may offer reassurance or direction.

This test measures a single blood value:

• Vitamin B12: the vitamin your body needs for energy, nerves, and blood production. To learn more about this value, read our explanation of vitamin B12.

The result shows how much B12 is circulating in your blood at the time of the draw.

A B12 measurement can indicate whether your value is on the low or high side. A low value can point to a deficiency and is often linked to fatigue and tingling.

A B12 that is too high can also be a reason to look further. Whether your B12 is too high may relate to other factors, such as supplement use or an underlying process your doctor will want to assess.

For this test, blood is drawn at a certified sample point. There are 650+ locations across the Netherlands, so you can often choose one close to home or work.

After ordering online, you pick a sample point and a time that fits your schedule. The blood is drawn by trained staff, usually in a few minutes.

You might consider this test when:

• you eat a plant-based diet and want to check your B12
• you feel persistently tired without a clear reason
• you notice tingling in your hands or feet
• you have had a deficiency before and want to track your value

Some people with a confirmed deficiency receive a vitamin B12 injection or supplements together with their doctor, and a measurement can then help show how your value is developing.

Your result shows your B12 values alongside a reference range, so you can see whether your value falls within the expected area. What counts as normal varies by lab, age, and situation, so numbers alone say little.

A value just below or above the range does not necessarily mean something. That is why a BIG-registered doctor always reviews your result and places it in context.

For a B12 measurement you usually do not need to fast, so the draw is easy to plan. If you take B12 supplements or have recently received an injection, mention it, as this can temporarily raise your value.

If you are unsure whether to change anything, check briefly with your doctor. Otherwise, no special preparation is needed.

Your result is usually online within 2 working days of the blood draw, with your value, a reference range, and a clear explanation, so you can quickly see where you stand.

Every blood test result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.