Vitamin B12 (Cobalamin) Blood Test
B12 is essential for nerve function and red blood cell production — and it's commonly low in vegetarians, vegans, and adults over 50.
What Vitamin B12 measures
Vitamin B12 (cobalamin) is required for DNA synthesis, red blood cell formation, and the myelin sheaths that insulate your nerves. It's only found in animal products, so people on plant-based diets need to get it from supplements or fortified foods. Absorption also drops with age and is reduced by some common medications.
Who should consider checking Vitamin B12
Have you noticed any of these:
- vegetarian or vegan
- older adult (absorption drops with age)
- fatigue or brain fog
- tingling or numbness in hands or feet
- after gastric surgery, or with autoimmune conditions affecting absorption
- currently or recently on metformin or long-term acid-suppressing medication
How the test works
Single blood draw, no fasting strictly required but morning is preferred. Stop B12 supplements 48–72 hours before testing for an accurate reading, if your doctor agrees. Results back same day.
What "normal" can look like
Reference ranges vary between labs but most define low at around 150–200 pmol/L. The grey zone in the lower-normal range can still cause symptoms in some people — context matters. If your doctor suspects functional deficiency despite a 'normal' B12, they may add markers like methylmalonic acid or homocysteine for clarity.
Where to get a Vitamin B12 test
Vitamin B12 is included in these panels:
- Vitamin & Mineral Panel — The essential nutrients behind energy, immunity and bone health — checked in one test. A$249
Frequently asked questions
Will my supplements skew the result?
Yes — recently taken B12 (especially injections or sublinguals) can elevate the reading temporarily. Stopping 48–72 hours before testing is recommended, with your doctor's input.
I'm vegan — how often should I test?
Once a year is sensible. After starting or changing a supplement, test 8–12 weeks in to confirm you're absorbing it.
What does long-term low B12 cause?
Long-term low B12 can lead to fatigue, cognitive issues, and nerve damage. Catching it early via a blood test means it's easily corrected with supplementation. Always discuss treatment with your doctor.
Related biomarkers
Guides
- Can You Get a Blood Test in Australia Without a GP Referral? (2026) — Yes — most common blood tests can be self-ordered in Australia. How direct-to-consumer pathology works, what's available, and when you should still see a GP first.
- How Much Does a Private Blood Test Cost in Australia? A Buyer's Guide (2026) — Private blood tests in Australia range from $35 for single biomarkers up to $500+ for comprehensive panels. What you're paying for, what drives the cost, and when private testing is worth it.