Skip to content

Complete Blood Count (CBC): What This Test Measures and Why Your Doctor May Order It

Published: August 9, 2026Updated: August 16, 2026

This test checks for IgA antibodies against Borrelia burgdorferi (Lyme disease bacteria) in the cerebrospinal fluid to help diagnose nervous system Lyme disease.

Quick summary

{"This test uses a sample of cerebrospinal fluid (CSF) taken via lumbar puncture","It detects IgA antibodies specific to Lyme disease bacteria","A positive result suggests Lyme disease has affected the nervous system"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
16479-8
Short code
BORRCSA
Synonyms
B burgdor IgA CSF Ql IA
Category
chemistry
Sample
csf
Container
Sterile CSF collection tube (polypropylene), tube #2 or #3 preferred to minimize blood contamination
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
0–120 years
Method
Immunoassay (Enzyme Immunoassay/EIA)
CPT
86618
SNOMED
415623000
Specimen volume
1-2 mL of cerebrospinal fluid
Stability
Room temperature: 2 hours; Refrigerated (2-8°C): 24 hours; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
Hemolysis max
200
TAT
24–72 hours
Order
routine

What is a complete blood count (CBC), and what does it measure in your blood?

The Borrelia burgdorferi IgA Antibody test looks for IgA antibodies in your cerebrospinal fluid (CSF). CSF is the clear fluid that surrounds your brain and spinal cord. IgA is a type of antibody (protein) that your immune system produces to fight infections. When Lyme disease bacteria (Borrelia burgdorferi) infect the nervous system, IgA antibodies may be present in the CSF.

How is the blood sample collected, and what can you expect during the blood draw?

Cerebrospinal fluid is collected through a procedure called a lumbar puncture (spinal tap). During this procedure, a healthcare provider inserts a thin needle between the bones in your lower back to withdraw a small amount of CSF. The area is numbed first to reduce discomfort. The sample is then sent to a laboratory for testing.

Why might your doctor order a CBC, and what symptoms or health conditions can it help evaluate?

Your doctor may order this test if you have symptoms of Lyme disease affecting the nervous system (neuroborreliosis). Symptoms may include facial drooping, limb weakness, numbness, severe headache, or meningitis. This typically occurs weeks to months after the initial tick bite.

Reference range

Negative; IgA antibodies to Borrelia burgdorferi are typically not detectable in CSF from healthy individuals. Positive results suggest intrathecal antibody production and neuroborreliosis.N/A

Specimen: csf

No fasting required. Lumbar puncture should be performed under sterile conditions by trained personnel. Inform patient of procedure risks including headache, infection, and bleeding.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

A positive IgA antibody result in CSF suggests that the patient has or recently had Lyme disease affecting the central nervous system. However, results should be interpreted alongside clinical symptoms, history of potential tick exposure, and other laboratory tests (such as blood Lyme disease testing). The test helps confirm neuroborreliosis, which requires antibiotic treatment. A negative result does not completely rule out Lyme disease, especially in early stages of infection.

Frequently asked questions

Is a lumbar puncture painful?
The procedure involves some discomfort. The lower back area is numbed with a local anesthetic, which may cause a brief burning sensation. You may feel pressure or a mild headache during the needle insertion. Most patients tolerate the procedure well.
How long does it take to get results?
Results are typically available within a few days to a week, depending on the laboratory. Your healthcare provider will contact you with the results.
What happens if my test is positive?
A positive result indicates that Lyme disease bacteria may have spread to your nervous system. Your doctor will discuss treatment options, which usually involves intravenous (IV) antibiotics for several weeks.
Do I need to fast before this test?
No fasting is required for this test. However, follow any specific instructions given by your healthcare provider.
  1. 1
    Lyme Disease - CDCSource
  2. 2
    Lyme Disease: Diagnosis and Treatment - Mayo ClinicSource
  3. 3
    Cerebrospinal Fluid (CSF) Analysis - MedlinePlusSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy