Interpret Your Vitamin B12 (Cobalamin) Results
Enter your B12 value below and get an instant, free AI interpretation — a plain-English explanation checked against WHO/IFCC reference ranges.
Medical Disclaimer
This AI-generated interpretation is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Results may vary based on individual health factors not captured here.
Always consult a qualified healthcare professional before making any health decisions. Read full disclaimer →
Vitamin B12 (Cobalamin) Normal Ranges
Vitamin B12 (cobalamin) is a water-soluble vitamin essential for DNA synthesis, nerve myelin sheath maintenance, and red blood cell formation.
| Reference Range | Unit | Notes |
|---|---|---|
| 200 – 900 | pg/mL | — |
Also reported in: pmol/L.
Critical (Panic) Values
Critical Low: < 100 pg/mL. Values outside these limits require immediate clinical attention.
Why Doctors Order the Vitamin B12 (Cobalamin) Test
Vitamin B12 deficiency causes megaloblastic anemia (large, dysfunctional red blood cells) and subacute combined degeneration of the spinal cord — a neurological condition causing progressive weakness, balance problems, and cognitive decline. The neurological damage can be irreversible if not treated promptly.
How to Enter Your B12 Result
Vitamin B12 (Cobalamin) can be reported in pg/mL or pmol/L. Choose the unit printed next to your result on the lab report so it is compared with the matching reference range.
What a Low or High B12 Can Be Associated With
Below the reference range
- Vegan and strict vegetarian diet (most common in young adults)
- Pernicious anemia (autoimmune destruction of intrinsic factor producing cells)
- Atrophic gastritis (reduced intrinsic factor and gastric acid)
- Post-gastric surgery (gastrectomy, bariatric surgery)
- Crohn's disease (terminal ileum is the absorption site for B12)
Above the reference range
- B12 supplements or injections
- Liver disease (release of stored B12)
- Myeloproliferative disorders (elevated B12-binding proteins)
- Solid organ cancers (paraneoplastic)
This interpreter flags a result at or below 100 pg/mL as a critical value. Results that extreme are uncommon — contact your doctor promptly, and seek urgent medical care if you feel unwell.
These are common associations, not a diagnosis. A single result is read alongside your symptoms, history and other tests — discuss it with your doctor.
What Can Change Your B12 Result
Before you read too much into a result, consider whether any of these applied:
- Recent B12 injection or high-dose oral B12 (raises level acutely)
- Folate deficiency (can co-occur with B12 deficiency)
- High-dose folate supplementation (may mask B12 deficiency anemia)
- Methotrexate (depletes folate and affects B12 metabolism)
Preparing for the test: No fasting required. B12 supplements should ideally be stopped for a few days before testing (if assessing status, not monitoring supplementation) for the most accurate result.
Symptoms That Often Prompt B12 Testing
- Macrocytic anemia: fatigue, pallor, shortness of breath
- Peripheral neuropathy: tingling, numbness, and burning in hands and feet
- Balance problems and difficulty walking (posterior column involvement)
- Memory problems and dementia (subacute combined degeneration)
- Depression and mood changes
Want the full clinical guide to Vitamin B12 (Cobalamin)?
Reference ranges, causes, symptoms, preparation, and FAQs.