NMDA Receptor Antibody NR1 CSF Test
About NMDA Receptor Antibody NR1 CSF Test
| Field | Value |
|---|---|
| Also Known As | Anti-NMDA Receptor Antibody Test, NMDA Receptor (NR1-subunit) Autoantibody Test, Anti-GluN1 Antibody Test, Anti-Glutamate Receptor Antibody CSF Test, NMDAR Antibody CSF Test |
| Sample Type | Cerebrospinal fluid (CSF) collected via lumbar puncture (spinal tap) |
| Fasting Required | No fasting required |
| Report Time | 5 to 14 days (may vary by laboratory) |
| Recommended For | All ages and genders; most commonly ordered for young females aged 12 to 45 years presenting with neuropsychiatric symptoms |
| Price | Starting at ₹6,500 |
What Is a NMDA Receptor Antibody NR1 CSF Test?
The NMDA Receptor Antibody NR1 CSF test detects specific antibodies in cerebrospinal fluid (the clear liquid surrounding the brain and spinal cord) that target a protein in the brain called the NMDA receptor. Doctors order this test when a patient shows sudden or unexplained neuropsychiatric symptoms that may point to an autoimmune condition affecting the brain. The sample is collected from the spinal canal through a procedure called a lumbar puncture. This test is also known as the Anti-NMDA Receptor Antibody CSF test or the NMDAR Antibody CSF test.
What Does a NMDA Receptor Antibody NR1 CSF Test Measure?
The NMDA NR1 antibody CSF test looks for one specific type of antibody in the cerebrospinal fluid. The table below explains what is being tested and why it matters.
| Parameter | What It Is | Why It Matters |
|---|---|---|
| NMDA Receptor NR1 IgG Antibody | An IgG (immunoglobulin G) antibody that attacks the NR1 subunit of the NMDA receptor, a brain protein that controls nerve cell communication | Normally absent in CSF; its presence may indicate an autoimmune attack on the brain |
The NMDA receptor controls how nerve cells communicate with each other. It plays a key role in memory, learning, and the brain's ability to adapt. When the immune system mistakenly produces antibodies against this receptor, it can disrupt normal brain function.
Why Is an NMDA Receptor Antibody NR1 CSF Test Done?
This test is ordered when a doctor suspects the brain is being affected by the immune system rather than an infection or other cause. Below are the most common reasons a doctor may request it.
Common Symptoms That May Require This Test
Doctors may recommend the autoimmune encephalitis CSF test when a patient presents with one or more of the following symptoms:
- Hallucinations (hearing or seeing things that are not there)
- Sudden and significant changes in behaviour or personality, often with agitation
- Impaired consciousness or confusion
- Seizures with no clear cause
- Abnormal movements, ranging from involuntary jerks to a state of near-immobility (catatonia)
- Irregular heart rate or unstable blood pressure (signs of autonomic dysfunction)
Conditions This Test Can Help Detect
The NR1 subunit antibody test is primarily used to identify the following conditions:
- Anti-NMDA Receptor Encephalitis, an autoimmune condition where the immune system attacks brain cells, causing complex neuropsychiatric symptoms
- Autoimmune limbic encephalitis, which affects the part of the brain that controls emotions and memory, and may or may not be linked to an underlying tumour
- NMDA-receptor autoimmune encephalitis accounts for 40 to 60% of all autoimmune encephalitis cases
NMDA Receptor Antibody NR1 CSF Test for Chronic Disease Monitoring
Once a patient tests positive for NMDA receptor antibodies, the test may be repeated during treatment to track progress. Falling antibody levels in follow-up tests are associated with a response to immunotherapy. Repeated testing helps the treating doctor assess whether the chosen treatment is working and guides further clinical decisions.
How to Prepare and What to Expect
The lumbar puncture procedure involved in collecting CSF is different from a routine blood draw. Here is what you should know before your appointment.
Do You Need to Fast?
No, fasting is not required before this test. You may eat and drink normally on the day of your appointment. That said, if additional tests have been ordered alongside this one, check with your doctor whether any of those require fasting.
Practical Tips Before Your Test
- Tell your doctor about all medications you are currently taking, especially blood thinners, as some may need to be paused before the lumbar puncture
- Inform your doctor if you have any bleeding disorders or low platelet counts
- Discuss any concerns about the procedure with your doctor beforehand; informed consent will be obtained before the lumbar puncture is performed
- Wear comfortable, loose clothing to your appointment
Step-by-Step Procedure
The following steps explain how the CSF sample is collected:
- You will be positioned either lying on your side or sitting upright; the lying-on-your-side position is generally preferred.
- The doctor will inject a local anaesthetic into the lower back area to numb the skin. You may feel a brief sting, after which the area becomes numb.
- A thin hollow needle is carefully inserted through the numbed skin into the space where the CSF is located. You may feel some pressure. You must remain still throughout this step.
- A small amount of CSF (roughly one tablespoon) drips out through the needle and is collected into sterile test tubes.
- The needle is removed, and a small dressing is placed over the puncture site.
- The collected CSF is labelled, stored under refrigerated conditions, and sent to the laboratory for analysis.
Factors That Can Affect Accuracy
Several factors can affect the quality of the sample and the reliability of results:
- A contaminated or blood-tinged CSF sample may be rejected by the laboratory
- Improper storage or transport of the sample at incorrect temperatures can affect results
- Repeated freezing and thawing of the sample reduces its stability
- Certain medications may influence antibody levels; always disclose your full medication history
Understanding Your NMDA Receptor Antibody NR1 CSF Test Results
Results from the NMDA receptor encephalitis test are reported as either negative or positive. Your doctor will always review these findings alongside your symptoms and medical history before drawing any conclusions.
| Parameter | Expected Result | Interpretation |
|---|---|---|
| NMDA Receptor NR1 IgG Antibody | Negative (not detected) | A positive result may indicate anti-NMDA receptor encephalitis or autoimmune limbic encephalitis; further titre reporting follows a positive finding |
These ranges are general guidelines. Your doctor will interpret your results based on your age, health history, and other factors. Always consult a qualified healthcare professional for personalised medical advice.
Results During Special Conditions
A few specific conditions can influence how results are interpreted:
Herpes Simplex Virus (HSV) encephalitis can trigger the production of NMDA receptor antibodies in the weeks following infection, sometimes leading to autoimmune encephalitis. Doctors will consider a recent viral illness when reviewing a positive result.
The condition predominantly affects young people (95% under the age of 45) and is four times more common in females than males. In women over 18, approximately half of cases are associated with an ovarian tumour called a teratoma. Higher antibody levels in CSF have been linked to more severe outcomes and the presence of such tumours.
CSF testing is more sensitive for detecting these antibodies than blood (serum) testing, making it the preferred sample for diagnosis.
How to Maintain Healthy Levels
While this condition requires medical management, the following general points support early recognition and care:
- Seek medical attention promptly if you or a family member experiences a sudden unexplained change in behaviour, memory loss, or new-onset seizures
- Early recognition of neuropsychiatric symptoms is associated with better recovery outcomes
- Attend all follow-up appointments if you are undergoing treatment, as repeated testing helps track antibody levels over time
Lupin Diagnostics NMDA Receptor Antibody NR1 CSF Test Price
The NMDA receptor CSF test price starts at approximately ₹6,500, and this test requires a visit to a Lupin Diagnostics centre as home collection is not available for CSF samples. The table below shows prices of this test in major cities across India:
| City | Approximate Price (₹) |
|---|---|
| Indore | ₹8,640 |
| Bangalore | ₹8,640 |
| Hyderabad | ₹8,640 |
| Pune | ₹8,640 |
| Mumbai | ₹8,640 |
Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
- Select the test on the Lupin Diagnostics website.
- Choose your city and preferred centre location.
- Visit the centre at your scheduled time for sample collection.
- Receive your report via email or WhatsApp within the stipulated turnaround time.
Frequently Asked Questions
The NMDA receptor antibody test is used to confirm a diagnosis of anti-NMDA receptor encephalitis, an autoimmune condition where the body's immune system attacks brain cells. It is ordered when a patient shows sudden neuropsychiatric symptoms such as hallucinations, seizures, or abnormal behaviour that cannot be explained by infection or other causes.
Studies show that CSF testing detects NMDA receptor antibodies in a higher proportion of patients than serum (blood) testing. In one study, all patients with confirmed disease had antibodies in CSF, while roughly 14% were missed on blood testing alone. For this reason, NMDAR antibody CSF testing is considered more accurate for diagnosis.
No fasting is required. You may eat and drink normally before your appointment. However, tell your doctor about all medications you are taking, as some may need to be paused before the lumbar puncture procedure.
Anti-NMDA receptor encephalitis has a strong female predominance. In women over 18 years, a significant proportion have an underlying ovarian tumour called a teratoma. Detecting and removing this tumour is often an important part of managing the condition.
Yes. Infections such as Herpes Simplex Virus (HSV) encephalitis can trigger the immune system to produce NMDA receptor antibodies in the weeks that follow. In patients recovering from viral encephalitis, doctors may order the autoimmune encephalitis CSF test if new neuropsychiatric symptoms appear.
The total turnaround time is typically 5 to 14 days. This includes transport of the CSF sample to the reference laboratory and the time taken to process and report results. Your doctor will notify you once the report is available.
No. A negative result does not fully rule out autoimmune limbic encephalitis. Other forms of autoimmune encephalitis exist and are caused by different antibodies. Your doctor will consider clinical findings, imaging results, and other tests alongside the NMDA receptor antibody NR1 CSF test to reach a diagnosis.
NMDA Receptor Antibody NR1 CSF Test: Booking, Price, and Results
