Methylmalonic Acid/Creatinine Ratio, 24-Hour Urine
A 24-hour urine test that measures methylmalonic acid relative to creatinine, helping evaluate vitamin B12 metabolism and some metabolic disorders.
["An elevated result may suggest vitamin B12 deficiency or another condition affecting methylmalonic acid metabolism, but results must be interpreted with other tests."]
Key facts at a glance
- LOINC
- 13775-2
- Short code
- Methylmalonate/Creat 24h Ur
- Synonyms
- Methylmalonate/Creat 24h Ur
- Category
- kidney
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 10 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What is this test?
This test measures methylmalonic acid, a substance produced during the breakdown of certain amino acids and fatty acids, in urine collected for 24 hours. The result may be adjusted using the urine creatinine level to help account for how concentrated the urine is.
Why might I need this test?
It may be ordered to help evaluate a possible vitamin B12 deficiency, particularly when symptoms or other blood tests suggest a problem. It can also be used when a clinician is evaluating suspected methylmalonic acidemia or another inherited metabolic condition.
How is the test performed?
You collect all urine for a full 24-hour period, usually in a labeled container provided by the laboratory or clinic. The urine is then sent to the laboratory, where methylmalonic acid and creatinine are measured and the result may be reported as a ratio.
How do I prepare for the test?
Follow the collection instructions carefully, including the starting time, ending time, and whether any urine collected before the period should be discarded. Tell your clinician about vitamin supplements, medications, antibiotics, and kidney problems because these can affect interpretation; do not stop prescribed treatment on your own.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An elevated methylmalonic acid result can occur with vitamin B12 deficiency and may also indicate a rare inherited metabolic disorder. Kidney impairment, certain medications, and some supplements can influence results, so an abnormal result should be interpreted alongside symptoms, blood tests, and other clinical findings.
Short name
24-Hour Urine Methylmalonic Acid
Frequently asked questions
Does an elevated result always mean I have vitamin B12 deficiency?
Why is a 24-hour urine collection needed?
Should I stop taking vitamin B12 or other supplements before the 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