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Methylmalonic Acid (serum)
268.00
The Methylmalonic Acid (Serum) test is a sensitive marker of vitamin B12 deficiency. It helps identify functional B12 deficiency even when B12 levels appear normal.
Turnaround time
5 days
Biomarkers count
1
Same-Day Appointments
UKAS Accredited Labs
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Under 18? Patients under 18 can only be seen at GB Medlabs and Clinilabs, Monday to Friday only.
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Details about Methylmalonic Acid (serum)
What is the Methylmalonic Acid (Serum) test?
The Methylmalonic Acid (MMA) test measures the level of methylmalonic acid in the blood. MMA is a substance that accumulates when vitamin B12 is insufficient at a cellular level.
Vitamin B12 is required for proper metabolism of certain fatty acids and amino acids. When B12 is deficient, MMA levels rise, making this test a highly sensitive and specific indicator of functional B12 deficiency.
This test is particularly useful when serum B12 results are borderline or symptoms persist despite “normal” B12 levels.
Why do I need a Methylmalonic Acid test?
Vitamin B12 deficiency can cause neurological, haematological, and cognitive symptoms and may not always be detected with standard B12 testing alone.
You may need this test if you experience:
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Fatigue or weakness
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Numbness or tingling in hands or feet
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Memory or concentration difficulties
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Balance problems
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Anaemia or abnormal blood counts
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Digestive conditions affecting absorption
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Borderline or inconclusive vitamin B12 results
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Monitoring response to B12 supplementation
The test helps confirm whether symptoms are related to functional B12 deficiency.
Benefits of the test
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Highly sensitive marker of B12 deficiency
Detects deficiency earlier than serum B12 alone. -
Identifies functional deficiency
Reflects cellular B12 status. -
Clarifies borderline B12 results
Reduces diagnostic uncertainty. -
Supports neurological symptom investigation
Explains nerve-related symptoms. -
Useful in absorption disorders
Detects deficiency due to malabsorption. -
Simple blood-based testing
Requires only one blood sample. -
Widely used in clinical practice
Standard test in B12 assessment pathways. -
Supports monitoring of treatment response
Helps track improvement with supplementation.
Step-by-step: How we offer testing
Clinic-based testing (UK-wide)
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Choose your nearest UK clinic
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Attend your appointment
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Blood sample taken by a clinician
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Sample sent to the laboratory
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Results are issued once analysis is complete
Home or hotel visit (+£60, UK-wide)
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Mobile phlebotomist attends your location
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Blood sample taken at home or hotel
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No clinic visit required
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Sample securely transported to the laboratory
Your results explained
Low / normal MMA
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MMA within reference range
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UK standard (typical): <0.28 µmol/L
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Suggests adequate cellular vitamin B12
Mildly elevated MMA
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Slight increase above reference range
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UK standard (typical): 0.28–0.40 µmol/L
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May indicate early or mild B12 deficiency
High MMA
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Significantly elevated MMA
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UK standard: >0.40 µmol/L
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Strongly suggests functional vitamin B12 deficiency
Kidney function can influence MMA levels and should be considered during interpretation.
How It Works
Simple steps to get your results
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Book Online
Choose your test online and book in seconds. Select your preferred clinic location or home visit option.
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Visit or Test at Home
Attend one of our UK or London clinics, arrange a home nurse visit, or use a finger-prick kit where available.
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Get Your Results
Your sample is analysed by accredited UK laboratories, with secure results delivered directly to you.
Take control of your health with London Blood Tests
WhatsApp UsHow to Prepare for Your Test
Follow these guidelines for accurate results
Sample Timing
Where possible, attend your blood test between 7am and 12pm. Please wait until any short-term illness or infection has fully resolved before testing. Avoid intense exercise for 24–48 hours beforehand, as this can affect certain markers.
Fasting & Hydration
Fasting is not always required, but some tests may recommend it. If fasting is advised, avoid food for 8–12 hours before your appointment and drink water only. Stay well hydrated, as this helps with sample collection and accuracy.
Medications & Supplements
Continue prescribed medications unless advised otherwise by your clinician. Avoid vitamin, mineral, or biotin supplements for at least 24–48 hours before your test, as these can interfere with results. If you are unsure about any medication or supplement, please let us know before your appointment.
Hormones & Menstrual Cycle
For hormone-related tests, timing within your menstrual cycle may be important. If relevant, follow any specific guidance provided on your test page.
If you have any questions or special circumstances, our team is happy to advise before your appointment.
Frequently Asked Questions
It reflects functional B12 status at the cellular level.
Yes, this indicates functional deficiency.
Yes, it helps explain nerve-related symptoms.
Yes, impaired kidney function may raise MMA.
Fasting is not usually required.
No, MMA is specific to B12 deficiency.
Yes, it is particularly useful in these groups.
Yes, levels should fall with effective supplementation.
Yes, B12 deficiency is more common with age.
It indicates functional vitamin B12 deficiency and supports further clinical evaluation.
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