Initializing Vogelview...
Performing medical cross-referencing...
Initializing Vogelview...
Performing medical cross-referencing...
Loading...
Also reported in: umol/L
Methylmalonic acid (MMA) is a byproduct of a specific B12-dependent enzyme reaction. When B12 activity is sufficient, MMA gets efficiently converted to succinyl-CoA and never accumulates in the blood. That's why MMA is considered a more reliable marker of cellular B12 status than a simple serum B12 level — serum B12 tells you how much vitamin is in the blood; MMA tells you whether the vitamin is actually doing its job. A normal MMA is strong evidence that you have enough B12 for your enzymes, regardless of what the serum B12 reading shows.
Methylmalonic acid (MMA) is a byproduct of a specific B12-dependent enzyme reaction. When B12 activity is sufficient, MMA gets efficiently converted to succinyl-CoA and never accumulates in the blood. That's why MMA is considered a more reliable marker of cellular B12 status than a simple serum B12 level — serum B12 tells you how much vitamin is in the blood; MMA tells you whether the vitamin is actually doing its job. A normal MMA is strong evidence that you have enough B12 for your enzymes, regardless of what the serum B12 reading shows.
No B12-deficiency flag from this marker. If your serum B12 was borderline, this is reassuring — the B12 you have is active and functioning.
MMA: {{value}} {{unit}} — normalA mildly elevated MMA can be the earliest detectable signal that B12 activity is starting to slip — often before serum B12 itself drops into the deficient range. This matters because by the time serum B12 is clearly low, the deficiency has usually already caused symptoms. The other thing that lifts MMA is kidney dysfunction — as kidney filtration drops, MMA clears more slowly, so the kidney itself can push this up without any B12 issue. Pregnancy can also produce mild elevations. So a borderline-high MMA is a conversation starter, not a conclusion.
Pair with a serum B12 level, a homocysteine (often elevated alongside in B12 insufficiency), and a creatinine/eGFR (a number that shows how well your kidneys filter your blood) to rule out the kidney contribution. If B12 supplementation is warranted, a short trial (2–3 months of oral or sublingual B12) followed by re-testing is usually the simplest path.
MMA: {{value}} {{unit}} — borderline elevatedA clearly elevated MMA is one of the more sensitive markers of functional vitamin B12 deficiency, and it's particularly useful when the serum B12 level is borderline or confusingly normal. The usual clinical picture: someone with fatigue, brain fog, tingling in the extremities, or mild anemia whose serum B12 reads "fine" but whose MMA (and often homocysteine) tells the real story. The other important cause is advanced kidney disease, where reduced filtration lets MMA accumulate independently of B12 status. Common B12-deficiency contexts include vegetarian/vegan diets without supplementation, chronic metformin or PPI use, pernicious anemia, and gastric bypass or other small-bowel surgery.
B12 supplementation almost always corrects this — oral high-dose (1,000–2,000 mcg daily) works for most people, while intramuscular B12 is used when absorption is a concern (pernicious anemia, post-gastric-bypass). Re-test MMA and B12 after 2–3 months of supplementation. If kidney function is impaired, discuss the expected residual elevation with your doctor.
MMA: {{value}} {{unit}} — elevatedUpload your lab report and get your actual values interpreted in plain English — instantly, with no medical training required.