Quick Answer
Blood tests reveal what symptoms can't — B12 deficiency, thyroid problems and diabetes all cause neurological symptoms. Here's how to read your results.
Medically reviewed by Dr. Jitendra Prasad Yadav • NMC 8029 • Kathmandu Neurology Clinic & Cognitive Center
Blood tests are one of the most powerful tools in neurological diagnosis — they can reveal reversible causes of symptoms that would otherwise be mistaken for permanent conditions. Understanding what your numbers mean helps you have informed conversations with your doctor.
Vitamin B12 — the nerve vitamin
B12 is essential for nerve function and red blood cell production. Deficiency causes tingling, numbness, balance problems, memory issues and fatigue. Levels below 200 pg/mL are deficient; 200–300 is borderline. Treatment is usually oral or injectable supplementation. Vegans, older adults and metformin users are at highest risk.
Thyroid function — TSH, T3, T4
TSH (thyroid stimulating hormone) is the screening test. High TSH with low T4 = hypothyroidism (underactive thyroid) — causes fatigue, depression, weight gain, cold intolerance and cognitive slowing. Low TSH with high T4/T3 = hyperthyroidism — causes anxiety, tremor, palpitations, weight loss and insomnia. Both affect brain function and can mimic neurological conditions.
HbA1c — your 3-month blood sugar average
HbA1c measures average blood sugar over 2–3 months. Below 5.7% is normal, 5.7–6.4% is prediabetes, above 6.5% is diabetes. High HbA1c causes peripheral neuropathy (tingling, numbness in feet/hands), increases stroke risk and accelerates cognitive decline. Diabetes is the leading cause of neuropathy.
Vitamin D — bone and brain health
25-hydroxyvitamin D below 20 ng/mL is deficient, 20–30 is insufficient. Deficiency causes muscle weakness, bone pain, falls and may contribute to cognitive decline. Treatment is supplementation — dose depends on severity.
When to get tested
If you have neurological symptoms — tingling, numbness, balance problems, memory changes, fatigue, mood changes — these tests can reveal treatable causes. At Kathmandu Neurology Clinic, we order targeted labs based on your symptoms and risk factors, not a blanket panel. Understanding your results helps you make informed decisions about treatment.
When to seek professional evaluation
Lab tests are interpreted in clinical context — a single abnormal value doesn't diagnose a condition. Discuss your results with your doctor.
This guide is educational and does not replace individual medical advice.
Frequently asked questions
Answers reviewed by Dr. Jitendra Prasad Yadav • MBBS, MD (Internal Medicine), FICN (Neurology), FCNV, FIHM • NMC 8029
Supplements only help when a deficiency is present; underlying cause-directed care is needed.
If the underlying cause is corrected early (e.g., improving glucose control, treating vitamin deficiency), improvement may occur. Long-standing neuropathy is often not fully reversible.
Brief slips without functional impact are often benign; persistent, progressive interference with daily tasks warrants assessment.
Yes, anxiety, depression, and poor sleep frequently impair attention and recall and improve when treated.
Progressive tingling starting in both feet, especially with diabetes, B12 deficiency or chemotherapy history, suggests peripheral neuropathy. Dr. Jitendra evaluates distribution (glove-stocking), underlying cause labs, and NCS/EMG when indicated. Burnout or anxiety alone rarely causes persistent stocking numbness — tar…
More: All FAQs → · Ask Dr. Jitendra →
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References & Review
Reviewed by Dr. Jitendra Prasad Yadav • Last reviewed: 2026-11-10
- International Classification of Headache Disorders, 3rd edition (ICHD-3).
- Harrison's Principles of Internal Medicine — Neurology sections.
- American Academy of Neurology guidelines for selected conditions (where applicable).
Content is educational and aligns with standard medical references; individual evaluation may vary. External links provide context and do not imply endorsement.