Vitamins & Nutrients
Methylmalonic Acid (MMA)
Vitamins & Nutrients
Functional B12 marker. More sensitive than serum B12 for detecting true deficiency.
VAT-exempt medical service
Methylmalonic acid is a compound produced during amino acid metabolism that accumulates when vitamin B12 is insufficient. While a serum B12 test is the standard first step, it can miss early or mild deficiency. The MMA test detects deficiency at the cellular level and is often ordered alongside homocysteine when serum B12 falls in the lower half of the reference range. Together these markers provide the most reliable assessment of functional B12 status. Up to 20 % of the elderly may have insufficient B12, and vegetarians, vegans, pregnant women and those with gut conditions are at elevated risk.
An MMA test is recommended when serum B12 is borderline or in the lower half of the reference range, especially if symptoms of B12 deficiency are present. It is also valuable as part of a comprehensive health check to uncover hidden deficiency early. Symptoms warranting testing include difficulty walking, mood swings, numbness, brain fog, fatigue, headaches, depression and anxiety.
What a high value can mean
Elevated MMA combined with elevated homocysteine and mildly decreased serum B12 strongly suggests early or mild B12 deficiency, indicating a lack of B12 availability at the tissue level. If homocysteine is elevated but MMA is normal, a folate deficiency is more likely. Very high MMA in infants may indicate the rare inherited condition methylmalonic acidaemia. Kidney disease can also falsely elevate MMA.
What a low value can mean
Low MMA is the expected, healthy result and indicates that vitamin B12 is functioning adequately at the cellular level. It is not considered clinically significant.
No advance preparation or fasting is required. Bring valid ID to the lab.
Order your test
Choose your test and pay online. Your lab referral is created straight away.
Give your sample
Visit any of our partner sampling locations. No appointment needed at most of them.
The lab analyses it
Your sample is analysed at an accredited Swedish laboratory.
Get your results
Your values appear in your account with reference ranges and an explanation of each marker.
MMA measures B12 activity at the cellular level, catching deficiency that serum B12 tests can miss. It is the most sensitive single marker for functional B12 status.
Yes. Testing both provides the most complete picture. A low serum B12 with high MMA confirms deficiency. A normal serum B12 with high MMA may reveal hidden cellular deficiency.
Yes. Impaired kidney function can elevate MMA independently of B12 status, so kidney function should be considered when interpreting results.
MMA is specific to B12 deficiency, while homocysteine can be elevated by deficiency in B12, folate or B6. Testing both helps distinguish which deficiency is present.