Differential Diagnosis: Vitamin B12
FND Nope
Moderator
B12 enables myelin production and nerve signalling; without it, nerves become damaged, causing neurological symptoms. As Dr J Stone acknowledges in the video clip below, testing for vitamin B12 levels should really be a routine part of a neurological investigation, something even a trainee should be aware of.
I am, however, concerned that neurologists, including Dr Stone, might not always be aware of the full extent of symptoms (even when rare) that can be
caused by this deficiency, as shown in the clip below.
The original full video from Dr J Stone can be viewed here. What I find interesting is that the callers, do not for a moment consider misdiagnosis, but rather assume comorbidity instead.
B12 Deficiency symptoms commonly include:
- Paresthesia (tingling or numbness in hands and feet)
- Gait disturbances and balance problems
- Muscle weakness
- Memory loss or cognitive impairment
- Mood changes (depression, irritability)
- Confusion or disorientation
- Peripheral neuropathy
- Ataxia (lack of coordination)
- Visual disturbances (optic neuropathy)
- Reflex changes (hyperreflexia or diminished reflexes)
- Seizures (rare, in severe deficiency - check B6 as well)
Psychosis and Seizures Attributed to Severe Vitamin B12 Deficiency: A Case Report" by Portillo et al. (published June 2, 2023)
When testing for B12, it’s important to consider not just serum levels, but also whether the body is actually absorbing and using it properly.
Key points:
- Serum B12 – measures total B12, but can be normal even if functional deficiency exists
- Active B12 (holotranscobalamin) – the fraction available for cells; more sensitive marker
- Methylmalonic acid (MMA) – rises when cells are B12-deficient; very sensitive
- Homocysteine – can be elevated in B12 deficiency, but also affected by folate and B6
- Intrinsic factor / parietal cell antibodies – for detecting pernicious anaemia
- Gastrointestinal absorption issues – e.g., gastric surgery, Crohn’s, celiac, chronic gastritis
- Medications affecting absorption – metformin, proton pump inhibitors
- Dietary intake – strict vegans at higher risk
Understanding Vitamin B12 Deficiency: A Growing Need for Awareness and Support
Vitamin B12 deficiency affects far more people than is commonly recognised, often going undiagnosed or misdiagnosed for years. It can lead to a wide range of symptoms — from fatigue and neurological issues to more subtle, hard-to-pinpoint changes in health — yet reliable information and proper support remain limited for many.
The B12 Society is a dedicated registered charity focused on changing this. Through clear, evidence-based education, they raise awareness among both the public and healthcare professionals, offer practical guidance on signs, symptoms and treatment, share the latest research updates, and provide a supportive community where people can connect, learn from real member stories, and find the resources they need.
Whether you're navigating symptoms yourself, helping a family member, or interested in understanding this often-overlooked condition better, their work helps break down barriers to accurate diagnosis and effective care.
To explore detailed information, current research, personal stories, and ways to get involved, visit the charity's website:
Visit The B12 Society