Biomarker
B12 and methylmalonic acid
B12 status can matter for cognition, neuropathy, fatigue, mood, and neuropsychiatric symptoms. One number is not the whole clinical story.
Review frame
How B12 and methylmalonic acid enters the review
Inputs
- Recent lab value with reference range
- Related symptoms
- Medication and supplement list
- Sleep pattern
- Relevant medical history
- What changed over time
Output
- Symptom and timeline summary
- Lab-pattern read in psychiatric context
- Medication, supplement, sleep, and substance review
- Psychiatric-medical differential
- Named pathway for care or monitoring
Not this
- Not emergency care
- Not a diagnosis from labs
- Not a medication or supplement change by website
- Not a replacement for primary care, psychiatry, or therapy
- Not proof that biology explains every symptom
Clinical read
B12 and methylmalonic acid can change the differential. It cannot carry the case by itself.
What the marker can show
B12 and methylmalonic acid help separate a simple serum value from possible functional deficiency, especially when neurological symptoms are present.
Where symptoms can blur
Brain fog, memory complaints, fatigue, low mood, or irritability Numbness, tingling, balance change, glossitis, or neuropathy symptoms Vegan diet, metformin, acid suppression, GI disease, or bariatric history
What it does not prove
This marker does not diagnose depression, anxiety, ADHD, insomnia, or burnout by itself.
When it matters more
Symptoms, timing, and risk decide how much weight this marker gets.
- Brain fog, memory complaints, fatigue, low mood, or irritability
- Numbness, tingling, balance change, glossitis, or neuropathy symptoms
- Vegan diet, metformin, acid suppression, GI disease, or bariatric history
Clinical discussion
What to discuss with a clinician.
- B12, MMA, folate, CBC pattern, and risk factors
- Whether neurological symptoms require prompt medical evaluation
- Medication and diet contributors that change interpretation
Common questions
Questions people ask before they start.
Can this marker diagnose the problem?
No. This marker can change what belongs in the differential. A responsible review still requires clinical history, symptoms, timing, medication context, risk review, and the appropriate clinician relationship.
What does the review actually give me?
A written psychiatric-medical synthesis: what appears more likely, what remains possible, what seems less likely, what needs another clinician, and what should be monitored or left alone.
Is this emergency care?
No. If symptoms are acute, dangerous, rapidly worsening, or involve possible self-harm, psychosis, mania, delirium, withdrawal, chest pain, neurologic symptoms, or medical instability, use emergency or urgent care.