Friday, 6 February 2026

P BLOOD NMDA

 A

Short answer: blood testing alone usually isn’t enough to confidently rule in or rule out anti-NMDA receptor encephalitis.


🧪 Why blood isn’t the full story

Doctors can check NMDA receptor IgG antibodies in blood (serum), but:

❌ Blood can miss real cases

Some people with confirmed disease have negative blood but positive CSF (spinal fluid).

❌ Blood can give false positives

Low-level antibodies sometimes show up in blood without actual brain inflammation.

✅ CSF (lumbar puncture) is more reliable

Spinal fluid is in direct contact with the brain, so it better reflects what’s happening neurologically.


📊 How doctors view it

ResultWhat it means
Blood negativeDoes NOT fully rule it out
Blood positiveSuggests it, but needs confirmation
CSF positiveStrong evidence (especially with symptoms)

Neurologists consider CSF the gold standard.


🧠 Why this matters

Anti-NMDA receptor encephalitis is diagnosed using a combo of:

  • Symptoms (psychiatric changes, seizures, confusion, movement problems)

  • MRI brain

  • EEG

  • CSF testing

  • Antibody tests

A blood result by itself doesn’t seal the deal either way.


🩺 So when is blood “good enough”?

Only in very low-suspicion situations where symptoms don’t fit the disease.
If doctors strongly suspect autoimmune encephalitis, they usually go ahead with a lumbar puncture even if blood is negative.


🚩 Big takeaway

If this test is being discussed because of sudden mental changes, seizures, or rapid neurological decline, you want a neurologist involved — not just a blood test.


If you want, tell me:

  • What symptoms are happening

  • Whether the blood result was positive, negative, or pending

That changes how serious the situation is.

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