24-Hour Vitamin B12 Intake Measurement (Urinary Excretion)
This test measures how much vitamin B12 your body excretes in urine over 24 hours, helping assess absorption and metabolic function.
["This test helps evaluate vitamin B12 balance and potential absorption issues."]
Key facts at a glance
- LOINC
- 81063-0
- Short code
- Vit B12 intake 24h Measured
- Synonyms
- Vit B12 intake 24h Measured
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 20
- Ref high
- 400
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- measured
- CPT
- 82670
- 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 Is Done
Your healthcare provider may order this test if you have symptoms like fatigue, numbness, or neurological concerns that could relate to vitamin B12 deficiency or malabsorption. It may also be used to monitor vitamin B12 status in certain chronic conditions or after treatments like gastric bypass surgery.
What to Expect Before the Test
No special preparation is needed. You’ll provide a 24-hour urine sample collected in a container, typically starting after the first morning urine void. Follow your provider’s instructions carefully to ensure accurate results.
How the Test Works
Your urine is analyzed to detect vitamin B12 levels excreted over 24 hours. This indirect measurement helps assess how well your body absorbs vitamin B12 from food.
What the Results Mean
Results are compared to expected ranges for healthy individuals. Low excretion may suggest poor absorption or metabolic issues, while high excretion could indicate over-supplementation or certain metabolic disorders.
Reference range
Premenopausal: 20-400 pg/mL; Postmenopausal: <30 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.
Clinical Significance: Vitamin B12 plays a critical role in red blood cell production, nerve function, and DNA synthesis. Deficiency can lead to anemia, neuropathy, or cognitive changes. This test helps identify absorption problems or metabolic imbalances that may require dietary adjustments, supplements, or medical intervention.
Short name
Vitamin B12 Urinary Excretion
Frequently asked questions
What causes abnormal vitamin B12 excretion?
How long does it take to get results?
Can I take vitamin B12 supplements before this test?
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 16, 2026. · Read our editorial policy