Vitamin B12 (Serum) – Mass Concentration
This test measures the amount of vitamin B12, an essential nutrient important for nerve function and red blood cell production, in your blood serum.
["Vitamin B12 levels help assess your risk for deficiencies that may cause fatigue, neurological issues, or anemia."]
Key facts at a glance
- LOINC
- 14685-2
- Short code
- Vit B12 SerPl-sCnc
- Synonyms
- Vit B12 SerPl-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 200
- Ref high
- 900
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms like numbness, tingling in hands/feet, weakness, unexplained fatigue, or if you have conditions like pernicious anemia, gastrointestinal disorders, or recent weight loss. It may also be part of routine screening for older adults or those with risk factors like poor diet, alcohol use, or certain medications.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the draw if your lab uses a fasting protocol. Wear a loose shirt for easy access to your arm.
How the Test Works
A small blood sample is taken from a vein in your arm. The serum portion is separated and analyzed to measure vitamin B12 concentration using a highly sensitive laboratory method.
What the Results Mean
Results are compared to a reference range, but exact values can vary by lab. Low levels may indicate deficiency, while high levels may suggest conditions like kidney disease or certain medications.
Reference range
NCBI: Vitamin B12 200-900 pg/mLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low vitamin B12 levels can lead to megaloblastic anemia (large, immature red blood cells), nerve damage (neuropathy), cognitive issues, or weakness. High levels may rarely indicate underlying health concerns like kidney disease or autoimmune disorders. Early detection and treatment can prevent serious complications.
Short name
Vitamin B12 Serum
Frequently asked questions
What causes vitamin B12 deficiency?
How is vitamin B12 deficiency treated?
Can vitamin B12 levels be affected by other conditions?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy