Methylmalonic Acid and Homocysteine Test
This test measures methylmalonic acid (MMA) and homocysteine together in a serum sample. Quest describes the pair as used in assessing vitamin B12 (cobalamin) and folic acid status, and in evaluating an elevated red blood cell size (macrocytosis).
About this test
Methylmalonic acid and homocysteine are two substances Quest measures together because both tend to rise when vitamin B12 or folate levels are low. Quest describes the pair as used to help evaluate and monitor B12 and folic acid status, and as often useful when a related blood finding, an elevated erythrocytic index called MCV, is also present.
The sample is 2.7 mL of serum. Methylmalonic acid is measured using mass spectrometry, and homocysteine is measured using an enzymatic method; the two results are reported together from the same specimen.
Test details
| Quest code | 91003 |
|---|---|
| Methodology | Methylmalonic Acid: Mass Spectrometry • Homocysteine: Enzymatic |
| Sample type | 2.7 mL serum |
| Collection | Quest patient service center |
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Quest resources
Additional details
What this test looks at
The test reports two values from the same serum sample: methylmalonic acid, measured by mass spectrometry, and homocysteine, measured by an enzymatic method. Quest describes the two together as more useful for evaluating B12 and folate status than either marker read alone.
Order online. No doctor's visit and no insurance needed. Your sample is collected at a Quest Diagnostics patient service center.
Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.
Frequently asked questions
What does this test measure?
It measures methylmalonic acid and homocysteine together in a serum sample, using mass spectrometry for MMA and an enzymatic method for homocysteine.
How is the sample collected?
Through a routine blood draw that produces a 2.7 mL serum sample.
Do I need to prepare for this test?
No preparation instructions are listed for this test. If a clinician has given you instructions, follow those.
Why are MMA and homocysteine measured together?
Quest describes both as used together in evaluating vitamin B12 and folic acid status, and notes the pair is often useful when an elevated red blood cell size (MCV) has also been found.
Is homocysteine relevant to anything besides B12 status?
Quest notes that an elevated homocysteine level is considered an independent risk factor for cardiovascular disease, in addition to its role in evaluating B12 and folate status.
Can I get the Methylmalonic Acid and Homocysteine test without a doctor's visit or insurance?
Yes. You don't need a referral or insurance. The test is $225, including the doctor's order and Quest blood draw. The $25 fee is waived at $149+. See how ordering works and our blood test cost guide.