About small fiber neuropathy
Because standard nerve conduction studies mainly measure large nerve fibres, they're often normal in SFN. Diagnosis usually relies on symptoms, a clinical examination and specialized tests such as a skin biopsy that counts nerve fibres, or tests of sweat function.
Common symptoms and challenges
- Burning, tingling, prickling or electric-shock pain, often starting in the feet
- Numbness, or unusual sensitivity to touch or temperature
- Changes in sweating, skin colour or temperature
- Autonomic symptoms such as light-headedness, digestive changes or a racing heart
Biological and environmental factors
Well established causes and associations: diabetes and prediabetes, vitamin B12 deficiency, thyroid disease, autoimmune conditions, celiac disease, excess alcohol and some medications. Rare inherited forms are linked to specific genes. In many people, no cause is found.
Emerging research: SFN has been found in subsets of people with fibromyalgia, POTS and other complex conditions, and researchers are studying immune-related mechanisms.
Laboratory testing
A clinician will usually check for treatable causes with blood tests such as glucose or HbA1c, vitamin B12 and thyroid function. Skin biopsy and autonomic testing are arranged through specialists.
How our tests may relate
- Celiac genetics: Celiac disease is one recognized association with neuropathy. A negative celiac HLA result makes celiac disease very unlikely.
- Medication response: Some medications used for nerve pain, such as certain tricyclic antidepressants, are broken down by enzymes studied in pharmacogenetics.
Important limitations: None of our tests can diagnose or rule out small fiber neuropathy, measure nerve fibres or identify its cause. A positive celiac genetic result means susceptibility, not celiac disease.
