Vitamin B12 (Active) Blood Test, from our experts to you.Dr Sam Rodgers MBBS, MRCGP
Chief Medical Officermeet our doctors
What is vitamin B12 and what does it do?
What can I learn from an active b12 test?
What are the symptoms of a vitamin B12 deficiency?
How to prepare for your test?
Frequently asked questions
What causes vitamin B12 deficiency?
The most common cause of vitamin B12 deficiency in the UK is pernicious anaemia, an autoimmune condition that prevents your body from absorbing vitamin B12 from food.
A deficiency can also be caused by a lack of vitamin B12 in your diet. Although this is increasingly uncommon, people who eat a diet low in dairy and animal products, such as those who eat a plant-based diet or have allergies, are at higher risk.
Other risk factors include taking certain medications such as metformin and omeprazole, having a gut autoimmune disease like Crohn's or coeliac disease, and being over 60.
How much vitamin B12 do I need?
The recommended daily amount of vitamin B12 varies depending on your age. The table below gives the daily average vitamin B12 amount recommended at each life stage.
|Age||Recommended amount (mcg)|
How can I improve my vitamin B12 level?
In some cases, making changes to your diet can improve your vitamin B12 level. Foods that are rich in vitamin B12 include meat, fish, eggs, and dairy products.
However, there are plant-based sources like yeast extract (such as Marmite) and fortified breakfast cereals. Find out more about plant-based diets and nutrition.
You may need to take a supplement to improve your level, and you should follow your GP’s advice carefully regarding treatments.
You can use our finger-prick B12 home test kit to check your level. This includes a full lab analysis of your blood sample and expert medical advice on any next steps. You can view your results and doctor’s comments on your MyMedichecks dashboard.
How can I check my vitamin B12 level at home?
What’s the difference between active vitamin B12 and total vitamin B12?
Measuring your total vitamin B12 might seem like the best way to check for a deficiency. However, only around 30% of the vitamin B12 in your body is available to use (known as active vitamin B12), while the rest is stored in an inactive form.
This means a normal total vitamin B12 result (including both active and inactive forms) could be misleading and may hide a deficiency. At Medichecks, we only measure your active vitamin B12 level to give you the most accurate result. Find out more about the difference between active and total vitamin B12.
What is pernicious anaemia?
Pernicious anaemia is an autoimmune disease that affects your body’s ability to absorb vitamin B12, causing vitamin B12 deficiency anaemia. Symptoms include feeling tired all the time, breathlessness, and mouth ulcers.
You’re more at risk of pernicious anaemia if you have a family history of the disease or another autoimmune condition, such as type 1 diabetes or a thyroid condition. If you’re concerned about pernicious anaemia, you can take a Pernicious Anaemia Blood Test.