Vitamin B12
supplementAn essential vitamin for nerves and red blood cells; low levels are common in older adults and metformin users.
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Lab test
What is a vitamin B12 test, and what is a normal B12 level?
A vitamin B12 test measures cobalamin in the blood to look for a deficiency, which can cause certain anemias and nerve problems. It is often ordered with folate when a CBC shows unusual red blood cells or there are neurologic symptoms. ARUP Laboratories lists a reference interval of 180 to 914 pg/mL; other labs differ.
What does the vitamin B12 test measure?
B vitamins help the body maintain normal metabolism, make healthy blood cells and keep the nervous system working. A vitamin B12 and folate test is often used for symptoms of certain types of anemia. MedlinePlus
Why is the vitamin B12 test ordered?
- ARUP describes its B12 test as an aid to detecting deficiency in people with macrocytic or unexplained anemia, or unexplained neurologic disease. ARUP Laboratories
- When symptoms suggest a shortfall, since B vitamin deficiency can cause nerve, muscle, memory and other problems. MedlinePlus
What are typical vitamin B12 ranges?
ARUP Laboratories publishes a single adult interval for vitamin B12. ARUP Laboratories
Reference ranges differ between laboratories and testing methods, and many also differ by age, sex, pregnancy or the phase of the menstrual cycle. The range printed on your own report is the one that applies to your result, and a clinician interprets it alongside your history.
| Group | Reference interval |
|---|---|
| All ages | 180 to 914 pg/mL |
ARUP points to methylmalonic acid (MMA) as an early and sensitive indicator of B12 deficiency that some references suggest. ARUP Laboratories
What can affect vitamin B12 results?
- You may need to fast for several hours before a vitamin B blood test. MedlinePlus
- Supplements and some medicines interact with B vitamins, so your provider considers your history before interpreting a result. MedlinePlus
When should you talk to a clinician about a vitamin B12 result?
- If a result is normal but symptoms persist, other tests may be needed; if a result is low, further tests look for why. MedlinePlus
DiscoverMedica explains what a test measures and what named sources publish. It does not interpret individual results; the clinician who ordered your test, or one you choose, does.
Where can you get a vitamin B12 test?
A clinician can order it as part of routine or follow-up care. Some services also let you order lab tests yourself; check that a service’s panel includes this marker, which laboratory runs it, and who reviews the result with you.
- Function HealthAnnual membership for broad lab panels, drawn at Quest sites or at home.
- Quest HealthOrder individual lab tests from Quest Diagnostics online, without a doctor’s visit. Lists “Vitamin B12 Test” at $49.00, as listed on its site, checked September 23, 2026.
Vitamin B12 Test: questions, answered
What is a normal vitamin B12 level?
ARUP Laboratories lists a reference interval of 180 to 914 pg/mL. Other laboratories may print different ranges, and some values near the lower limit are followed up with other tests, such as methylmalonic acid, so read your result against your own report and discuss it with the clinician who ordered it.
Why is B12 tested with folate?
Both vitamins are needed to make healthy red blood cells, and a shortfall in either can cause similar anemias. MedlinePlus notes that a combined vitamin B12 and folate test is often used when symptoms suggest certain types of anemia. ARUP offers B12 on its own and a combined B12 and folate test.
Can B12 be too high?
MedlinePlus says large amounts of B vitamins can cause health problems or reflect an underlying condition such as liver disease, and that B vitamin supplements can affect how some medicines work. A high value is discussed with the clinician who ordered the test.
Sources
Last reviewed October 7, 2026. Every source above was checked on or before that date. Educational information only, not medical advice; it does not replace a conversation with a licensed clinician. DiscoverMedica does not employ clinicians.
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