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Decoding Your B12 Test Results: What Do Those Numbers Really Mean?
Published: Apr 21, 2024
Understanding your vitamin B12 test results can be confusing. Let's break down what those numbers mean and when you might need additional testing.
What's a Normal B12 Level?
Generally, a B12 level above 300 pg/mL is considered normal. Levels between 200-300 pg/mL are borderline and may require further investigation. Anything below 200 pg/mL is typically considered deficient. However, these ranges can vary slightly between labs.
When Numbers Don't Tell the Whole Story
Sometimes, B12 levels alone aren't enough to diagnose deficiency. Your body might have trouble using B12 even if blood levels appear normal. In these cases, doctors may order additional tests like methylmalonic acid (MMA) or homocysteine levels. These compounds increase when your body isn't getting enough usable B12.
Factors That Can Affect Your Results
Certain conditions can cause falsely low or high B12 readings. Pregnancy, taking oral contraceptives, or having multiple myeloma can lead to misleadingly low levels. Conversely, liver disease or certain blood cancers might cause falsely high readings. It's crucial to interpret results in the context of your overall health and symptoms.
Beyond B12: Other Tests to Consider
If B12 deficiency is suspected, your doctor might also check your folate levels, as these deficiencies often occur together. A complete blood count (CBC) can reveal anemia, which is common in B12 deficiency. In some cases, tests for intrinsic factor antibodies might be ordered to check for pernicious anemia, a common cause of B12 deficiency.
Frequently Asked Questions
Annually if you're at high risk; otherwise, as recommended by your doctor.
No, some cases require additional testing beyond just B12 levels.
Usually not, but follow your doctor's specific instructions.
Yes, B12 supplements can elevate your levels and mask deficiency.
Excess B12 is generally considered safe, but very high levels may indicate other health issues.
The Bottom Line
B12 testing is valuable but sometimes requires additional context and follow-up for accurate diagnosis.
References
- Devalia V, Hamilton MS, Molloy AM, British Committee for Standards in Haematology. Guidelines for the diagnosis and treatment of cobalamin and folate disorders. Br J Haematol 2014; 166:496.
- Green R. Vitamin B12 deficiency from the perspective of a practicing hematologist. Blood 2017.
- Stabler SP. Clinical practice. Vitamin B12 deficiency. N Engl J Med 2013; 368:149.
This article has been reviewed for accuracy by one of the licensed medical doctors working for Doctronic. Always discuss health information with your healthcare provider.
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