How much does Vitamin B12 (Active) (Venous) cost at Wimpole Street?

£81 — the standard price that applies to everyone. There is no discounted members’ tier at Wimpole Street and nothing to join. Where a venous draw is needed, a phlebotomy fee is shown on the page before you book and is charged once per visit however many tests are taken.

Should I stop my B12 tablets before testing?

If you want to know whether your diet alone is sufficient, stopping a supplement for a few weeks before the sample will give a clearer answer. If you are checking that a supplement is working, carry on taking it. Never stop prescribed injections without discussing it with the prescriber.

Why measure folate in red cells rather than serum?

Serum folate reflects what you have eaten over the last few days and can rise after a single leafy meal. Red cell folate averages intake over the lifespan of the red cell, roughly three months, so it gives a steadier picture of long-term status.

Can someone under 16 have a B12 test here?

Medical services at Wimpole Street are for patients aged 16 and over. Children and younger teenagers should be seen through their NHS GP, or NHS 111 if the matter cannot wait.

How long until I get the result?

Total B12 and serum folate are typically reported within one to two working days of arrival at the laboratory. Active B12, methylmalonic acid and intrinsic factor antibodies take longer, sometimes up to a week. The laboratory report is released to your secure portal with reference ranges as soon as it is complete.

What is the difference between total and active B12?

Total B12 counts all of the vitamin in your blood, including a portion bound to a protein that cells cannot take up. Active B12 measures only the usable fraction bound to transcobalamin, so it can be more informative when the total result is borderline.

📍 Wimpole StreetOpening 1 Oct

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Individual Test

Vitamin B12 (Active) (Venous) Blood Test Marylebone

From 1 October 2026 — until then book at South Kensington or St Paul's. South Kensington · St Paul's

20 min appointment

Results: 1 day"

Venous blood

£81

+ £50 phlebotomy fee (per visit)

Price

£81

+ £50 phlebotomy (per visit)

Confidential Results

Secure online portal

Fast Results

1 day"

Professional Service

Experienced phlebotomists

Wimpole Street, Marylebone (opening 1 October 2026)

22 Wimpole Street, Marylebone, London W1G 8GQ

020 7183 0692

wimpolestreet@md.co.uk

Opens 1 October 2026

Opening hours from 1 October 2026

Monday: 9am – 6pm
Tuesday: 9am – 8pm
Wednesday: 9am – 6pm
Thursday: 9am – 8pm
Friday: 8am – 5pm
Saturday: 10am – 4pm
Sunday: Closed

Bond Street — about 6 minutes (Central, Jubilee & Elizabeth lines)
Oxford Circus — about 7 minutes (Central, Bakerloo & Victoria lines)

Wimpole Street, Marylebone

Within the vitamin B12 and folate range at Wimpole Street, the Vitamin B12 (Active) (Venous) is the test to consider when the question concerns cobalamin level, B12 deficiency and red blood cells. It costs £81, and once the Marylebone clinic opens on 1 October 2026 a nurse or phlebotomist takes the venous blood sample (serum), with the laboratory typically reporting in 1 day. Medical services are for patients aged 16 and over, self-referral with no GP referral needed, and the laboratory report is delivered to your secure portal.

vitamin B12 and folate · Wimpole Street

Vitamin B12 (Active) (Venous)’s place in vitamin B12 and folate testing

Sample: venous blood sample (serum)
Laboratory turnaround: 1 day
Appointment: 20 minutes
Standard price: £81 + £50 phlebotomy per visit

Who considers Vitamin B12 (Active) (Venous)

People often consider this test if they follow a vegan or largely plant-based diet, because B12 comes almost entirely from animal sources.
Pins and needles, numbness, poor balance or memory changes are symptoms that commonly prompt a check.
Anyone taking metformin or long-term acid-suppressing medication may want to know their level, as both can reduce absorption.
A full blood count showing large red cells (a high MCV) frequently leads to B12 and folate being measured next.
Those with coeliac disease, Crohn’s disease or previous stomach surgery often monitor B12 periodically.

What Vitamin B12 (Active) (Venous) measures

Vitamin B12 (Active) (Venous) is most often requested in connection with cobalamin level, B12 deficiency and red blood cells, which is why it sits within the vitamin B12 and folate group at Wimpole Street.

These tests measure the two vitamins most closely tied to red blood cell production and nerve function. Total B12 reports everything circulating in the blood, whereas active B12 (holotranscobalamin) measures the fraction cells can use; folate can be measured in serum for recent intake or in red cells for a longer-term average. Methylmalonic acid and intrinsic factor antibodies are add-on tests that help to explain why B12 might be low.

Preparing for your Vitamin B12 (Active) (Venous)

1Fasting is not required for B12 or folate, though a morning appointment keeps conditions similar between repeat tests.
2If you have recently had a B12 injection or a high-dose oral supplement, tell the nurse; levels can read high for weeks afterwards.
3Biotin in large doses can interfere with some immunoassays; pausing it for two days is a sensible precaution.

Sample for this test: venous blood sample (serum).

Understanding your Vitamin B12 (Active) (Venous) results

A low B12 or folate can indicate dietary shortfall, poor absorption or, less commonly, an autoimmune cause such as pernicious anaemia. Values in the grey zone between clearly low and clearly adequate are common, and active B12 or methylmalonic acid may help to decide whether cells are actually short of the vitamin. High readings are usually explained by supplements and are rarely a concern on their own.

B12 and folate results are read together with your full blood count, symptoms and diet, and a normal serum level does not entirely exclude a functional deficiency.

Related areas of testing at Wimpole Street: full blood count, iron and ferritin, nutrition, vitamins and trace elements, coeliac disease and gluten.

Pricing

Vitamin B12 (Active) (Venous)

Individual test

£81

Phlebotomy Fee

Blood draw by qualified phlebotomist (per visit)

£50

Total

£131

Payment is collected at the clinic. The phlebotomy fee is charged once per visit, regardless of the number of tests booked.

How it works at Wimpole Street

From booking the Vitamin B12 (Active) (Venous) to reading your result

1
Choose your test
Select the Vitamin B12 (Active) (Venous) and any others you want run from the same visit. Until 1 October 2026 the identical test can be booked at South Kensington or St Paul’s.
2
Nurse-led sample
From 1 October 2026 the venous blood sample (serum) is taken at 22 Wimpole Street, Marylebone by our nursing team, led by Precious Agbonmamwen, Registered Adult Nurse (NMC 20H1641E). Identity is checked and any preparation questions answered first.
3
UKAS-accredited laboratory
The sample travels to a UKAS-accredited partner laboratory, whose methods and reference ranges match those used across the NHS and private sectors.
4
Laboratory report to your secure portal
The laboratory report is released to your secure portal — typically from 24 hours; the laboratory quotes 1 day for this test. It shows each value against the reference range and flags anything outside it; discuss the report with your GP or a clinician.

Marylebone, W1

Why test at Wimpole Street

Wimpole Street Medical & Dental opens at 22 Wimpole Street on 1 October 2026. Medical services are for patients aged 16 and over; registration with the CQC is in progress ahead of opening.

Wimpole Street, Marylebone (opening 1 October 2026)

22 Wimpole Street, Marylebone, London W1G 8GQ

020 7183 0692

wimpolestreet@md.co.uk

Opens 1 October 2026

Bond Street — about 6 minutes (Central, Jubilee & Elizabeth lines)
Oxford Circus — about 7 minutes (Central, Bakerloo & Victoria lines)

Registration with the CQC is in progress ahead of opening; our South Kensington and St Paul’s clinics are CQC registered.
Self-referral: you choose the test and book directly — no GP referral is needed, and the laboratory report is yours to take to your GP or a clinician.
The same catalogue already runs at South Kensington and St Paul’s, so you can test now and move your records to Marylebone later.

More vitamin B12 and folate tests

Other tests often considered alongside Vitamin B12 (Active) (Venous)

All blood tests at Wimpole Street

Frequently Asked Questions

A venous blood sample (serum). A nurse or phlebotomist collects it at 22 Wimpole Street, Marylebone from 1 October 2026; the appointment allows time for identity checks and any preparation questions. The laboratory quotes 1 day for this test.

Ready to Book Your Test?

Wimpole Street opens 1 October 2026. Register your interest for the Marylebone diary, or book the same test now at South Kensington or St Paul's.

Important information about the Vitamin B12 (Active) (Venous) at Wimpole Street

Medical services at Wimpole Street Medical & Dental are for patients aged 16 and over.
This is a self-referral service: you choose the test and book directly — no GP referral is needed.
Nurse-led by Precious Agbonmamwen, Registered Adult Nurse (NMC 20H1641E), who oversees sample-taking standards, infection control and the patient pathway. The nursing team does not interpret results.
A laboratory result is not a diagnosis and this page is not a substitute for medical advice. We do not provide clinical interpretation of results — please discuss your report with your GP or a clinician, particularly if a value is flagged or you have symptoms.
CQC registration for Wimpole Street is in progress ahead of the opening on 1 October 2026; our South Kensington and St Paul’s clinics are CQC registered.
Your results are held on a secure portal and treated as strictly confidential, except where disclosure is required by law.
If you are seriously unwell, call 999. For urgent advice that is not an emergency, call NHS 111.