Methylmalonic Acid (MMA) Test
Reviewed
Also called: MMA test, methylmalonic acid test
This test measures the amount of methylmalonic acid (MMA) in your blood or urine. High MMA levels can be a sign of a vitamin B12 deficiency. The test is also used in newborn screening to check for methylmalonic acidemia, a rare genetic disorder.
Specimen: Blood or urine
Urgent safety information
If your baby has moderate or high levels of MMA, it may mean they have methylmalonic acidemia. If not treated, it can cause life-threatening complications. Discuss results with your child's provider promptly.
Why this test may be ordered
- To diagnose a vitamin B12 deficiency if you have symptoms such as fatigue, diarrhea, dizziness, shortness of breath, loss of appetite, tingling in hands/feet, mood changes, confusion, irritability, or pale skin.
- As part of newborn screening to check for methylmalonic acidemia.
Preparation and collection
You may need to fast (not eat or drink) for several hours before the test. Follow any special instructions from your provider.
Blood draw from a vein in the arm; for newborns, a heel stick. Urine collection may be a 24-hour sample or a random sample.
Blood test: slight pain or bruising at the needle site, which goes away quickly. For a newborn heel stick: a little pinch and possible small bruise that goes away quickly. Urine test: no known risk.
Understanding results
Your provider will consider your symptoms, medical history, and the results of other blood tests to interpret your MMA levels.
- Higher-than-normal MMA: Higher-than-normal levels of MMA may mean you have a vitamin B12 deficiency. Limitation: The test cannot show how much of a deficiency you have. Next step: Your provider may compare your results with other tests including a homocysteine blood test and/or vitamin B tests.
- Lower-than-normal MMA: Lower-than-normal levels of MMA are not considered a health problem. Limitation: Lower-than-normal levels are not common and are not considered a health problem. Next step: No specific follow-up is needed for this result alone.
- Moderate or high MMA in a newborn: Moderate or high levels of MMA in a newborn may mean they have methylmalonic acidemia, a rare genetic disorder. Limitation: If not treated, methylmalonic acidemia can cause life-threatening complications. Next step: If your baby is diagnosed with this disorder, talk to your child's provider about treatment options.
- The test cannot show how much of a deficiency you have.
- Results must be interpreted together with your symptoms, medical history, and other tests (such as homocysteine and vitamin B tests).
What to do next
If you have questions about your results, talk to your provider. For a baby diagnosed with methylmalonic acidemia, discuss treatment options with the child's provider.
- What do my MMA levels mean in combination with my symptoms and other test results?
- If my baby has high MMA levels, what follow-up testing or specialist referral is needed?
- How often should I be tested if I am at risk for vitamin B12 deficiency?
Evidence source
U.S. National Library of Medicine: Methylmalonic Acid (MMA) Test