Vitamin B12 (Serum) 24-Hour Urinary Excretion Rate
This test measures how much vitamin B12 your body excretes in urine over 24 hours. It helps assess how well your kidneys are handling vitamin B12 after it’s been absorbed.
["This test helps diagnose kidney function related to vitamin B12 metabolism."]
Key facts at a glance
- LOINC
- 2169-1
- Short code
- Vit B12 Cl 24h Ur+SerPl-vRate
- Synonyms
- Vit B12 Cl 24h Ur+SerPl-vRate
- 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 Is Done
Your healthcare provider may order this test if you have symptoms like fatigue, numbness, or balance issues that could suggest vitamin B12 deficiency or kidney problems. It may also be used to evaluate kidney function in people with chronic vitamin B12 deficiency or certain genetic conditions affecting absorption.
What to Expect Before the Test
No special preparation is needed. You may collect your urine over 24 hours in a clean container, starting after you wake up the next morning. Store the urine in a refrigerator until you return it to the lab.
What Happens During the Test
The test involves collecting all urine produced in a 24-hour period. The lab will analyze the urine sample to determine the amount of vitamin B12 excreted.
What the Results Mean
Results help determine if your kidneys are properly processing vitamin B12. Abnormal results may indicate kidney dysfunction or other metabolic issues.
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.
Clinical Significance: Vitamin B12 Urinary Rate
Short name
Vitamin B12 Urinary Rate
Frequently asked questions
What questions might you have about this test?
This test is less commonly used than serum vitamin B12 levels. Doctors may prefer it if they suspect kidney involvement in vitamin B12 metabolism or if other tests are inconclusive. It helps assess how well your kidneys filter and handle vitamin B12 after absorption.
A serum vitamin B12 test measures the amount of vitamin B12 in your blood, while this test measures how much is excreted in urine over 24 hours. The urinary rate can provide additional insight into kidney function and vitamin B12 processing.
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