The vitamin B12 test measures, directly in blood, total serum cobalamin, most of which is bound to haptocorrin and unavailable to cells. Practitioners use it to screen clients with fatigue, neurological or mood symptoms, plant-based diets, or metformin or acid-suppressant use. Supplements and fortified drinks raise it, and pregnancy or the pill lower it without true deficiency. Practitioners can order it through the Vively practitioner platform.
| Test type | Measured in a blood sample |
|---|---|
| Measurements required | Vitamin B12 only |
| Sample and collection | Blood draw at a collection centre |
| Preparation | No fasting is needed for this test. |
| Turnaround | About 3 to 5 business days |
| Available through | Vitamins & Trace Elements. Available in: Energy Panel, Weight Insight Panel, Essential Nutrients Test, Vitamin B12 Test. |
| Pricing | Price on sign-up |
| Results | Returned in the Vively practitioner platform, beside your client's other markers |
What are the Vitamin B12 reference and optimal ranges?
| Typical lab reference | Vively optimal | |
|---|---|---|
| Adults | 120 to 1000 pmol/L | 450 pmol/L or above |
Labs differ, and many flag the lower part of their range as borderline, so read the result against the range and comments on the client's report (RCPA guidance). The optimal range is a screening target, not a diagnostic cut-off.
Check a client's Vitamin B12 result
Enter the value from your client's lab report to see where it sits against the typical lab range and the Vively optimal range.
A guide only, not a diagnosis. One result is a starting point: read it with symptoms, history and a repeat test. Labs differ, so check the result against the range on your client's report. Nothing you enter is stored or sent.
How do you arrange Vitamin B12 testing through Vively?
- Get verified. Practitioners with a recognised qualification or membership (ATMS, NHAA, ANTA, Dietitians Australia, NSA, CMA or Ahpra registration) can request free practitioner access.
- Choose a panel. Log in to the practitioner platform and pick a panel that includes Vitamin B12, or build your own. Add-on pricing shows when you sign up.
- Client collects. Your client collects at a partner collection centre, with their request on their phone or printed.
- Review results. Results come back to you in the practitioner platform, beside your client's other markers, ready for the follow-up consult.
Which Vively panels include Vitamin B12?
Log in to the practitioner platform to view a panel in full, or build and save your own from 100+ tests and panels.
- Log in to view this panelEnergy Panel6 markers · NutrientsPrice on sign-up
- Log in to view this panelWeight Insight Panel8 markers · Heart & metabolicPrice on sign-up
- Essential Nutrients Test12 markers · NutrientsPrice on sign-upVitamin B12SeleniumVitamin DRed blood cell folateRed Blood Cell MagnesiumRed Blood Cell ZincRed Blood Cell CopperCaeruloplasmin+4 moreLog in to view this panel
Why does the optimal range sit there?
Our 450 pmol/L floor sits well above the 120 pmol/L lab limit, clear of the indeterminate zone where total B12 is a weak test.
Only about 10 to 30% of B12 circulates as active holotranscobalamin, so a lower-range result can coexist with raised methylmalonic acid (MMA) and homocysteine, the markers of tissue deficiency.
The British Society for Haematology guideline (Devalia et al., 2014) and NICE (2024) both call results near the cut-off indeterminate and recommend a second-line test in symptomatic people.
Above 450 pmol/L, functional deficiency from low supply is less likely unless assay interference applies. No trial shows that lifting a replete client to 450 pmol/L improves outcomes.
What should Vitamin B12 be read with?
- ContextB12 in the lower range with high MCV
Possible B12 or folate deficiency affecting red cell production; check RBC folate and refer if haemoglobin is low.
- ContextBorderline B12 with low holotranscobalamin
Supports early or functional deficiency; MMA or homocysteine through the GP can confirm it.
- ContextNormal B12 with neurological symptoms
Does not exclude deficiency, particularly in pernicious anaemia, where intrinsic factor antibodies can falsely raise some assays.
- ContextB12 above 1000 pmol/L without supplements
Often seen with liver disease or kidney impairment and, less commonly, blood disorders; needs GP review.
- LowLow B12 with low ferritin
Possible atrophic gastritis, coeliac disease or a restrictive diet affecting both.
What can affect a Vitamin B12 result?
- Oral B12, injections and fortified energy drinks raise serum B12 for days (oral) to months (injections)
- Pregnancy and the oral contraceptive pill lower total B12 by reducing haptocorrin, without true deficiency
- Intrinsic factor antibodies in pernicious anaemia can give falsely normal results on some assays (Carmel and Agrawal, 2012)
- Metformin, proton pump inhibitors, H2 blockers and repeated nitrous oxide use reduce absorption or inactivate B12
- High-dose biotin can interfere with some immunoassays
When should you refer the client to their GP?
- B12 below the lab range, or borderline with numbness, tingling, poor balance, memory change or a sore tongue
- Low or borderline B12 with high MCV or low haemoglobin
- Suspected pernicious anaemia or coeliac disease, or previous gastric or bariatric surgery
- Unexplained B12 above 1000 pmol/L in a client not taking supplements
- Before folic acid in anyone with possible B12 deficiency, as folate can correct the anaemia while nerve damage progresses
How should a client prepare for a Vitamin B12 test?
Copy or print this to send to your client.
Preparing for your Vitamin B12 test
- No fasting is needed for this test.
- Tell your practitioner about any B12 supplements or injections, and when you last had one, as recent use can raise your result.
- Tell your practitioner if you take biotin (often found in hair, skin and nail formulas), as high doses can distort the result.
- Take your pathology request to any of 4,000+ collection centres. Bring it printed or on your phone.
- Keep taking prescribed medicines as usual unless your doctor tells you otherwise.
- Results usually take about 3 to 5 business days and come to your practitioner. Book your results appointment for after that.
How do practitioners use Vitamin B12 with clients?
Ask what the client already takes before reading the result: many energy, multivitamin and pre-workout products contain B12, and a high number may only reflect last week's intake. For borderline results with symptoms, add holotranscobalamin and involve the GP; repeating total B12 alone adds little.
Vitamin B12 FAQs
Can a naturopath, nutritionist or dietitian order a vitamin B12 test through Vively?
Yes. Add it to any client panel on the Vively practitioner platform. It sits in Vitamins & Trace Elements and is also in Energy Panel, Weight Insight Panel and Essential Nutrients Test. Add-on pricing shows when you sign up. No account yet? Request free access.
Should I order holotranscobalamin as well as total B12?
Yes, when the answer will change what you do. Total B12 is the better-validated screen and the result most GPs act on. Holotranscobalamin measures the active fraction and falls earlier in developing deficiency. Together they reduce borderline calls. HoloTC rises within days of oral intake, so record recent supplement use before reading either.
How long after stopping B12 supplements should I test?
There is no agreed washout. Oral supplements lift serum B12 within days, and injections can keep it high for months. If you need the unsupplemented level, discuss a break of several weeks with the client's GP; otherwise test on the current regimen and record the product and timing. Prescribed injections should not be stopped for testing without GP input.
Can a normal total B12 rule out deficiency in a client with neurological symptoms?
No. Only about 10 to 30% of circulating B12 is active holotranscobalamin, so total B12 is a weak test at the low end. Add holotranscobalamin and involve the client's GP, who can order MMA or homocysteine to confirm tissue deficiency.
Why is total B12 low in a client who is pregnant or on the pill?
Pregnancy and the oral contraceptive pill lower total B12 by reducing haptocorrin, the binding protein that carries most of it, without true deficiency. Holotranscobalamin is often normal in this situation, which makes real deficiency less likely. Read a low total alongside holotranscobalamin, MCV and symptoms before drawing a conclusion.
References
- Royal College of Pathologists of Australasia. RCPA Manual: Vitamin B12. Source
- Devalia V, Hamilton MS, Molloy AM. Guidelines for the diagnosis and treatment of cobalamin and folate disorders. British Journal of Haematology. 2014.
- National Institute for Health and Care Excellence. Vitamin B12 deficiency in over 16s: diagnosis and management (NG239). 2024. Source
- Carmel R, Agrawal YP. Failures of cobalamin assays in pernicious anemia. New England Journal of Medicine. 2012.