Methylmalonic Acid (Blood)
Does this test have other names?
What is this test?
This test measures the amount of a substance called methylmalonic acid (MMA) in your
MMA is typically made in tiny amounts when you digest protein. Your body makes large
amounts of MMA if you have a drop in the amount of vitamin B-12. MMA is excreted through
Your body needs B-12 to make red blood cells and to help your central nervous system
work as it should. Low levels of B-12 can cause anemia. This is when your body does
not make enough red blood cells.
This test is used to diagnose a mild and early shortage of vitamin B-12. A high level
of MMA can mean that that you have a low level of B-12. Vitamin B-12 deficiency is
the most common cause of MMA production.
Foods that can increase B-12 levels include red meats, shellfish, fish, dairy, and
cereals fortified with the vitamin. If you are a strict vegetarian, you may be at
higher risk for a B12 deficiency. If you are pregnant and are a vegetarian, you may
want to take a B-12 supplement. This is especially important if you plan to exclusively
breastfeed your baby. Otherwise, your child may also be especially susceptible to
a B-12 deficiency.
Why do I need this test?
You may have this test if your healthcare provider thinks you have a vitamin B-12
deficiency. You may also have this test if you have symptoms of neuropathy, or loss
of movement. This can include numbness and tingling in your hands and feet.
Other symptoms of B-12 deficiency include:
You may also have this test if your healthcare provider suspects that you have methylmalonic
acidemia. This is an uncommon metabolic disorder in which your body can't process
certain fats and proteins. The disease is usually diagnosed in infants and can be
mild or life-threatening.
What other tests might I have along with this test?
Your healthcare provider may also order a homocysteine blood test. If your homocysteine
levels are high, your provider may also order a test to measure your folate (folic
acid) concentrations. Your provider may also order an evaluation of intrinsic factor
and a complete blood count.
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses
to do the test. Even if your test results are different from the normal value, you
may not have a problem. To learn what the results mean for you, talk with your healthcare
Results are given in micromolars per liter (mcmol/L). A normal test result is less
than 0.2 mcmol/L. It means that you likely have enough vitamin B-12 in your body.
If your MMA levels are higher, you may have a B-12 deficiency.
Higher MMA levels are common in pregnancy. Higher MMA levels may also be caused by
kidney disease. This is usually because less MMA is sent into your urine, causing
it to accumulate in your blood.
Infants may have extremely high levels of MMA because of a condition called methylmalonic
acidemia. B-12 levels typically return to normal with treatment.
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection,
bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight
stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
Other factors aren't likely to affect your results.
How do I get ready for this test?
You don't need to prepare for this test. But be sure your healthcare provider knows
about all medicines, herbs, vitamins, and supplements you are taking. This includes
medicines that don't need a prescription and any illicit drugs you may use.