Methylmalonic Acid (MMA) Test

This test measures the amount of methylmalonic acid (MMA) in your blood or urine. MMA is a substance made in small amounts when you digest protein. MMA is needed for metabolism, which is the process that your body uses to change food into energy.

Vitamin B12 plays an important role in metabolism. Part of this role is breaking down MMA into substances that help with metabolism. If your body doesn't have enough vitamin B12, it will continue to make more MMA than is broken down.

High MMA levels can be a sign of a vitamin B12 deficiency. Vitamin B12 deficiency can happen if you are not eating enough B12 in your diet or if your body has difficulty absorbing it. Your body cannot make vitamin B12 on its own, so you have to get it from the foods you eat.

This vitamin is found in foods such as: Seafood such as fish, clams, and oysters; Dairy products; Chicken; Eggs; Meat; Vitamin B12 is also found in some fortified foods, meaning the food has vitamins added to it. It's also available as a supplement. Vitamin B12 also helps to make red blood cells.

A deficiency can lead to health issues, including anemia. This is a condition in which your blood has a lower-than-normal amount of red blood cells.

Why this test is done

You may need this test if you have symptoms of a vitamin B12 deficiency. These may include:

• Fatigue
• Diarrhea
• Dizziness
• Shortness of breath
• Loss of appetite
• Tingling in hands and/or feet
• Mood changes
• Confusion
• Irritability
• Pale skin

You might be at a higher risk for B12 deficiency if you:

• Are a strict vegetarian or vegan
• Have a digestive disease, such as celiac disease or Crohn's disease
• Are a person with an alcohol use disorder (AUD)
• Are older than 75 years
• Have Sjogren's syndrome, a disease that causes dry eyes and mouth
• Have had certain types of stomach or intestinal surgery

If you have a new baby, they will probably be tested as part of a newborn screening.

How to prepare

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.

Sample type

Blood Urine

Other names for this test

MMA