Vitamin B12 Test: Why It Is Checked and What Results Mean
Vitamin B12 is needed for red blood cell formation and normal nerve function. A B12 test measures the amount of vitamin B12 in the blood, and low levels can cause fatigue, tingling, and a type of anemia called macrocytic anemia. Reduced intake, absorption problems, and certain medications can lower B12. Because some people have low-normal levels along with symptoms, clinicians may also check methylmalonic acid or homocysteine for a clearer picture of tissue-level deficiency.
Key Takeaways
- Vitamin B12 is needed for red blood cell formation and normal nerve function.
- A B12 test measures the amount of vitamin B12 in the blood.
- Low B12 can cause fatigue, tingling, and a type of anemia called macrocytic anemia.
- Low levels can result from diet, absorption problems, or certain medications.
- Because some people have low-normal levels with symptoms, clinicians may also check methylmalonic acid or homocysteine.
Frequently Asked Questions
Do I need to fast for a B12 test?
Fasting is usually not required.
What causes low B12?
A vegan or vegetarian diet, reduced stomach acid, pernicious anemia, celiac disease, and some medications can lower B12.
Can I order a B12 test directly?
Yes, B12 testing is available through direct-access labs. A clinician should interpret low results.
Does B12 testing include folate?
Some panels combine B12 and folate, since both relate to anemia and nerve health.
Sources
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