Definition of Methylmalonic acid test:

Methylmalonic acid is a substance produced when proteins (amino acids) in the body break down. A test can be done to measure the amount of methylmalonic acid in your blood.

How the test is performed:

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

The blood is then sent to the laboratory for analysis.

How to prepare for the test:

No special preparation is necessary.

How the test will feel:

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed:

Your doctor may order this test if there are signs of certain genetic disorders, such as methylmalonic acidemia. (Testing for methylmalonic acidemia is often done as part of a newborn screening exam.)

This test may also be done with other tests to check for a vitamin B12 deficiency.