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.
Specimen: Blood or urine
Urgent safety information
If your baby has moderate or high levels of MMA, it may mean that they have methylmalonic acidemia. If it's not treated, it can cause life-threatening complications.
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 your test. Your provider will let you know if there are any special instructions to follow.
MMA levels may be checked in blood or urine. During a blood test, a health care professional will take a blood sample from a vein in your arm, using a small needle. During a newborn screening, a health care provider will clean your baby's heel with alcohol and poke the heel with a small needle. MMA urine testing may be ordered as a 24-hour urine sample test or a random urine test.
There is very little risk to you or your baby during an MMA blood test. You may experience slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. There is no known risk to having a urine test.
Understanding results
If a result or symptoms suggest an emergency, get emergency medical help right away.
Your provider will consider your symptoms, medical history, and the results of other blood tests.
- Higher-than-normal MMA: If your results show higher-than-normal levels of MMA, it may mean you have a vitamin B12 deficiency. Limitation: The test can't show how much of a deficiency. Next step: To help make a diagnosis, 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 common and are not considered a health problem. Limitation: Your provider will consider your symptoms, medical history, and the results of other blood tests. Next step: If you have questions about your results, talk to your provider.
- Moderate or high MMA in a newborn: If your baby has moderate or high levels of MMA, it may mean that they have methylmalonic acidemia. Limitation: If it's not treated, it 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.
- 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
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.
U.S. National Library of Medicine: Methylmalonic Acid (MMA) Test