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Methylmalonic Acid/Creatinine Ratio, 24-Hour Urine

Published: August 9, 2026Updated: August 16, 2026

Measures methylmalonic acid relative to creatinine in urine collected for 24 hours, often to help evaluate vitamin B12 metabolism.

Quick summary

["An elevated result may indicate vitamin B12 deficiency or, rarely, an inherited disorder affecting methylmalonic acid metabolism."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
25115-7
Short code
Methylmalonate/Creat 24h Ur-sRto
Synonyms
Methylmalonate/Creat 24h Ur-sRto
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 the amount of methylmalonic acid in urine compared with the amount of creatinine. Creatinine is used as a reference because urine output and concentration can vary. It is commonly used when vitamin B12 deficiency or a metabolism disorder is suspected.

Why might I need this test?

A clinician may order this test to investigate low vitamin B12 levels, symptoms suggestive of B12 deficiency, or an inherited condition that affects methylmalonic acid metabolism. It may also be used alongside other vitamin B12 tests.

How is the test performed?

You collect all urine produced during a full 24-hour period. The laboratory then measures methylmalonic acid and creatinine and may calculate their ratio. The collection period and any preservative instructions must match those provided by the laboratory.

How do I prepare for the test?

Begin the collection at the time specified by the laboratory and collect every urine sample for the next 24 hours. Refrigerate the container and return it as instructed. Follow any diet or medication guidance provided by your clinician, and do not start or stop supplements unless told to do so.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

24-Hour Urine Methylmalonic Acid/Creatinine Ratio

Frequently asked questions

Does this test diagnose vitamin B12 deficiency by itself?
No. An elevated result can support a diagnosis, but vitamin B12, folate, and other relevant tests are usually considered along with symptoms and medical history.
Why is creatinine included in the test?
The ratio helps account for differences in urine concentration and hydration. Creatinine is a reference marker rather than the substance being evaluated for vitamin B12-related changes.
What if I miss part of the 24-hour urine collection?
An incomplete collection can make the result unreliable. Tell the laboratory or your clinician when the collection ended and ask whether the test should be repeated.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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