How to prepare
Fasting for at least 8 hours before your blood draw is recommended. MMA levels can be slightly affected by protein intake. If you are currently supplementing B12 or receiving B12 injections, your MMA will reflect your treated state. If you want to assess your baseline before starting treatment, test before initiating supplementation.
After the test
Share your result with your GP or specialist. An elevated MMA, particularly alongside low serum B12, confirms functional deficiency and guides treatment decisions — whether oral supplementation, sublingual B12, or injections depending on the cause and severity. If kidney disease is present, this will be factored into result interpretation.
Your test results will be available in your private dashboard. If there are any urgent issues, we'll let you know so you can follow up with your health professional.
Understanding results
MMA is measured in micromoles per litre (µmol/L). Normal fasting values are typically below 0.28–0.40 µmol/L (laboratory-specific ranges apply).
- Elevated MMA: Indicates functional B12 deficiency at the cellular level. The degree of elevation broadly reflects the severity and duration of deficiency. Can also be elevated in kidney disease (which reduces MMA excretion), so renal function should be considered when interpreting results.
- Normal MMA: In a symptomatic patient with low serum B12, a normal MMA suggests the serum B12 result is reliable and functional deficiency is unlikely. In a patient with borderline serum B12 and symptoms, normal MMA provides reassurance.
- MMA versus homocysteine: Both rise in B12 deficiency. Homocysteine also rises in folate and B6 deficiency. Elevated MMA with normal homocysteine is more specifically B12-related.
