Home kit
Active Vitamin B12 Test
Active B12 (holotranscobalamin), the fraction of vitamin B12 your cells can actually use.
- Doctor-reviewed results
- Laboratory analysis
- 1 to 2 working days from lab receipt
- No fasting required
What’s included
1 marker measured
Active vitamin B12
The part of your vitamin B12 that your cells can actually use. B12 supports nerves and red blood cells. UK guidance accepts either active or total B12 as a first test, and recent supplements or injections can raise the result without fully treating a deficiency.
Overview
Most of the B12 in your blood is bound to a protein that cannot deliver it into cells, and active B12 measures only the part your cells can take up. UK guidance accepts it as a first test for B12 deficiency, and people choose it when tiredness, pins and needles or a plant-based diet is the reason for asking.
Most of the B12 in blood is bound to a protein that cannot deliver it into cells. Active B12 measures only the part that is available to them, and UK guidance accepts either active or total B12 as the first test when a deficiency is suspected. Long-term acid-reducing tablets and metformin can both lower B12, and the report explains what a low result usually leads to.
Who this is for and who it isn’t
Who it’s for
- Adults aged 18 and over
- Vegans and anyone on a largely plant-based diet without a supplement
- People on long-term acid-reducing tablets or metformin
Who it isn’t for
- This is one marker, not an investigation of tiredness. Iron stores, thyroid function and a blood count are often checked first when tiredness is the question. Active B12 also cannot say why a level is low: diet, absorption and pernicious anaemia all look the same from this number alone, and telling them apart needs your GP.
- If you are already taking B12 tablets or having injections, the result may reflect the supplement rather than your own levels.
- Anyone with a new, severe or worsening symptom: contact your GP or call NHS 111. A test you buy today is not a substitute for being examined.
Common reasons people choose this test
- Tiredness that has not improved with rest
- Pins and needles, numbness or burning in the hands or feet
- A vegan or largely plant-based diet without a supplement
- Long-term acid-reducing tablets or metformin
- Poor concentration or low mood you want a physical explanation checked for
These are reasons people choose to test, not signs that something is wrong. A result is one part of a picture your doctor puts together with your history and an examination.
What your result looks like
Every result is shown with the unit and the reference range exactly as the laboratory reported it, with the doctor’s note underneath.
- Active vitamin B12▼ Low
- Result
- 30 pmol/L
- Range
- >37.5
| Marker | Result | Units | Range | Flag |
|---|---|---|---|---|
| Active vitamin B12 | 30 | pmol/L | >37.5 | ▼ Low |
Doctor’s note (example)
Active B12 is below the range. Common in vegans and with acid-suppressing medicines; a clinician would usually discuss replacing it, by tablet or injection, and it is worth telling your GP.
Values above are examples. Your report shows your own results with the laboratory’s units and reference range for your age and sex, reviewed, signed and released by a GMC-registered doctor.
How it works
- Your kit arrivesPosted to your door, with instructions and what you need to send your sample back.
- You take your sampleFinger-prick sample at home, or a clinic blood draw, your choice
- The laboratory analyses itYour sample is processed for the measurements included in this test. Lab processing typically takes 1 to 2 working days from receipt of your sample.
- A doctor reviews and releases itA GMC-registered doctor reads every result and signs the report before it reaches you.
- Sample
- Home finger-prick kit
- Preparation
- No fasting required
- Who it's for
- Any sex · ages 18+
How to prepare
What we can and can’t tell you
The reference range beside each result is the laboratory’s own. A result in range is not a clean bill of health and a result outside it is not a diagnosis. Most ranges cover about 95% of healthy people, so about 1 in 20 healthy people fall just outside any one range. No test result replaces an examination or your own doctor’s judgement, and none of these panels is a cancer screening programme.
Read the full note
The reference range printed beside each of your results is the laboratory's own, and it is the range that applies to your result. We do not apply a second range of our own, and we do not tell you that a result the laboratory reported as normal is nonetheless too low or too high. If you see a claim elsewhere that your result ought to sit inside a narrower band than the one the laboratory printed, treat it with caution and ask your doctor.
Some assays cannot give an exact figure above or below a certain point, and those results are reported the way the laboratory sends them, for example as a value greater than a stated number. A result in range is not a clean bill of health, and a result outside a range is not a diagnosis: most reference ranges are set to cover about 95% of healthy people, so some healthy people fall just outside them. No blood test replaces an examination, a scan or your own doctor's judgement, and none of these panels is a screening programme for cancer.
If you have a symptom that is new, severe, or getting worse, contact your GP or NHS 111 rather than waiting for a test result. In an emergency call 999.
Frequently asked questions
How is this different from a total B12?
Total B12 counts everything in the blood, including the large share bound to a protein that cannot release it to cells. Active B12 counts only the part attached to the carrier that can. UK guidance accepts either as a first test, and both can give a borderline result that needs a further test to settle.
Do supplements affect it?
Yes. Supplements taken as tablets or injections can raise it. A result taken while supplementing tells you the supplement is reaching your blood, not what your body manages without it.
Do I need to fast?
No. Fasting makes no difference to B12, and any time of day is fine.
What usually happens if it comes back low?
The doctor's note explains the result and the usual next step, which is a GP conversation about why it is low and how it would be replaced. Nerve symptoms are the reason not to sit on a low result, and the report says so.
How long do results take?
The laboratory typically takes 1 to 2 working days from receiving your sample. This does not include kit delivery, sample collection or return postage. A doctor reviews your results before they are released.
Can I choose a home kit or a clinic?
Both, it is your choice at checkout. Either collect a finger-prick sample at home with the posted kit and send it back as the instructions explain, or book a clinic appointment and have a trained clinician take the sample for you.
Is a doctor involved?
Yes. Every result is reviewed by a GMC-registered doctor who signs it off and explains what it means and what to do next.
Is it confidential?
Your results are available through your secure patient portal. Our privacy policy explains how your information is handled and when it may be shared to provide your care.
What happens to my sample and results?
Your sample is analysed at a UKAS-accredited laboratory (ISO 15189). A GMC-registered doctor then reads every result and signs the report before it is released, so nothing reaches you unreviewed. There is no option to receive results without a doctor reading them first. The report arrives in your secure portal in plain English: each result with its unit and the laboratory's own reference range, and the doctor's note on what the set means read together. If a result sits outside its range the report says so and explains what usually happens next, which is most often a conversation with your own GP, who can act on it alongside your history and examination. Most reference ranges are set to cover about 95% of healthy people, so about 1 in 20 healthy people fall just outside any one of them. On a report with many results it is common for one to sit just outside its range, and a single number on its own rarely tells the whole story. If a result needs urgent attention, the reviewing doctor is alerted straight away and we contact you by phone the same working day rather than leaving it in the portal for you to find. If a specific result needs rechecking, the reviewing doctor says so in your report.
People also check
See all longevity & prevention tests
Advanced Thyroid Check with AntibodiesA full thyroid panel: TSH, total and free T4, free T3, and two antibodies that can point to an immune reaction against the thyroid gland.£163.00Includes clinic appointmentView test
Advanced Vitamin CheckThe widest vitamin panel here: ten direct blood measurements covering vitamins A, D and E, beta carotene, and the B vitamins including red-cell folate and active B12.£587.00Includes clinic appointmentView test
Fasting preferredAdvanced Well Person Check with CholesterolThe widest well person panel here: general chemistry, blood count, thyroid, blood sugar, iron and vitamin D, with the full cholesterol breakdown added.£214.00Includes clinic appointmentView test