methylmalonic acid

An MMA blood test measures methylmalonic acid (MMA) levels in your blood. It’s mainly used to check for vitamin B12 deficiency.

Why it’s done

MMA builds up in your body when you don’t have enough vitamin B12, so this test helps:

• Detect early or mild B12 deficiency
• Confirm unclear B12 test results
• Investigate symptoms like fatigue, numbness, memory issues, or anemia

What results mean

• High MMA levels → often indicate vitamin B12 deficiency
• Normal MMA levels → usually means B12 levels are adequate

Why not just test B12 directly?

Regular B12 blood levels can sometimes look “normal” even if your body isn’t using B12 properly. MMA is more sensitive in those cases.

Other causes of high MMA

Not always B12 deficiency—can also be due to:

• Kidney problems
• Rare metabolic disorders