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Vitamin B12 Test

⚠️ Update approaching🔬 Evidence: StrongHematology
Diğer adları: B12, B12 level, Cobalamin
⚠️

Discuss your test results with your doctor. This page is for informational purposes only and does not provide a diagnosis.

⚡ Key Facts

• Measures blood vitamin B12 (cobalamin) level • Normal: generally 200–900 pg/mL (148–664 pmol/L) • Important for nerve function, red blood cell production, and DNA synthesis • Deficiency is common in elderly, vegetarians/vegans, and those with malabsorption

🧪 What Does This Test Measure?

The vitamin B12 test measures total cobalamin in the blood, a vitamin essential for nerve function, red blood cell production, and DNA synthesis.

📋 Why Is It Ordered?

Ordered for B12 deficiency evaluation, unexplained anemia or neurological symptoms investigation, and monitoring of supplementation or treatment.

🔧 Preparation

No special preparation is generally required in most situations; specific practices may vary by laboratory.

📊 Reference Ranges

Normal: generally 200–900 pg/mL (148–664 pmol/L) Borderline low: 200–300 pg/mL — may warrant additional testing Deficient: <200 pg/mL ⚠️ Reference ranges vary by laboratory.

⬆️ High Values

Elevated B12 is commonly seen with supplementation. Unexplained elevation without supplements may occasionally be associated with liver disease or myeloproliferative disorders.

⬇️ Low Values

Low B12 may be associated with inadequate dietary intake, malabsorption conditions, pernicious anemia, or certain medications.

⚙️ What Can Affect Results?

B12 supplements, medications (metformin, PPIs), diet, age, gastric/intestinal surgery, and assay method may affect B12 results.

🔬 Evidence Summary

Strong evidence: 2 guidelines, 2 systematic reviews/meta-analyses, 4 reviews.

📚 Most Important Studies on This Topic

1

Diagnosis, Treatment and Long-Term Management of Vitamin B12 Deficiency in Adults: A Delphi Expert Consensus

Guideline· Journal of Clinical Medicine · 2024 · PMID: 38673453

2

Vitamin B12 Deficiency from the Perspective of a Practicing Hematologist

Review· Blood · 2017 · PMID: 28360040

3

Clinical Practice: Vitamin B12 Deficiency

Review· New England Journal of Medicine · 2013 · PMID: 23301732

✅ Key Takeaways

💡

What you learned: B12 deficiency is common and may cause anemia and neurological symptoms. Borderline results may warrant additional testing with methylmalonic acid or homocysteine.

⛔

A B12 result alone may not fully reflect functional B12 status. Additional biomarkers and clinical context may be needed.

🔬 Sources Used on This Page

8 sources · Most recent publication: 2024
📋
Guideline
Expert society and guideline recommendations
2
sources
📊
Systematic review / meta-analysis
Combined analysis of multiple studies
2
sources
📖
Review
Comprehensive topic evaluation
4
sources
Overall assessment: Evidence level for this topic is strong. This page is supported by 2 guidelines, 2 systematic reviews/meta-analysis, 4 reviews.

📝 Questions to Ask Your Doctor

Be prepared for your appointment. Add questions to your list.

📋 References

[PMID: 38673453] Diagnosis, Treatment and Long-Term Management of Vitamin B12 Deficiency in Adults: A Delphi Expert Consensus. Journal of Clinical Medicine, 2024.
[PMID: 37060552] Vitamin B12 Deficiency and Use of Proton Pump Inhibitors: A Systematic Review and Meta-Analysis. Expert Review of Gastroenterology & Hepatology, 2023.
[PMID: 37984968] Vitamin B12. BMJ, 2023.
[PMID: 28360040] Vitamin B12 Deficiency from the Perspective of a Practicing Hematologist. Blood, 2017.
[PMID: 28660890] Vitamin B12 Deficiency. Nature Reviews Disease Primers, 2017.
[PMID: 24942828] Guidelines for the Diagnosis and Treatment of Cobalamin and Folate Disorders. British Journal of Haematology, 2014.
[PMID: 25502588] The Role of Metformin on Vitamin B12 Deficiency: A Meta-Analysis Review. Diabetes & Metabolism, 2014.
[PMID: 23301732] Clinical Practice: Vitamin B12 Deficiency. New England Journal of Medicine, 2013.
Last reviewed: 3/26/2026
Next review: 3/26/2027

⚖️ Comparisons

B12 vs Ferritin→

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⚖️ This page does not replace medical advice. Make treatment decisions with your doctor.
Content is based on scientific studies indexed in PubMed and current clinical guidelines.