Complete Blood Count (CBC) Test: What It Is, Why It Is Done, and How the Sample Is Collected
This test checks for IgG antibodies against Borrelia burgdorferi (the bacteria that causes Lyme disease) in joint fluid using immunoblot technique.
{"Detects immune response to Lyme disease bacteria in joint fluid","Used to confirm Lyme disease involvement in joint inflammation","Performed when Lyme arthritis is suspected","Sample is collected via joint fluid aspiration (arthrocentesis)","Positive result suggests the immune system has been exposed to Lyme bacteria"}
Key facts at a glance
- LOINC
- 30017-8
- Short code
- LYME58IGG
- Synonyms
- B burgdor58kD IgG Snv Ql IB
- Category
- chemistry
- Sample
- fluid
- Container
- Sterile screw-cap vial or cryogenic tube; leak-proof, sterile container
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Immunoblot (Western Blot)
- CPT
- 86617
- SNOMED
- 398103003
- Specimen volume
- 1-2 mL synovial fluid
- Stability
- Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days; Avoid repeated freeze-thaw cycles
- Hemolysis max
- 300
- TAT
- 48–168 hours
- Order
- routine
What is a complete blood count (CBC) test and what does it measure in my blood?
This test looks for IgG antibodies specifically targeting the 58kD protein of Borrelia burgdorferi, the bacterium that causes Lyme disease. The test is performed on synovial (joint) fluid, not blood. An immunoblot (Western blot) technique is used to detect these specific antibodies, which indicates that your immune system has responded to the Lyme disease bacteria.
Why might my doctor order a complete blood count (CBC) test during a routine checkup or when I am not feeling well?
This test is primarily ordered when a patient has symptoms of Lyme arthritis, such as joint swelling, pain, and stiffness (typically in the knee, but other joints may be affected). It helps doctors determine if Lyme disease is the cause of joint inflammation, especially in areas where Lyme disease is common or when other Lyme tests (like blood tests) may have given inconclusive results.
How is the blood sample for a complete blood count (CBC) test collected, and do I need to do anything to prepare?
A healthcare provider will collect synovial fluid from the affected joint using a procedure called arthrocentesis. The area is cleaned and numbed, then a needle is inserted into the joint to withdraw fluid. This fluid is then sent to a laboratory for analysis. You may feel pressure or mild discomfort during the procedure.
What do the results of a complete blood count (CBC) test mean, and what can high or low values tell my doctor?
A positive result indicates that IgG antibodies against the 58kD protein of Borrelia burgdorferi were detected in your joint fluid. This strongly suggests that Lyme disease bacteria are present in the joint and causing your symptoms. A negative result means no antibodies were detected, but this does not completely rule out Lyme disease—early infection or treatment with antibiotics may affect results. Your doctor will interpret these results in the context of your symptoms, exposure history, and other test findings.
Reference range
Negative (Reactive bands not detected at 58kD antigen)N/A
No special preparation required. Inform physician of any antibiotics or immunosuppressive therapy prior to collection.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is clinically significant for diagnosing Lyme arthritis, a manifestation of late Lyme disease that affects the joints. Detection of specific IgG antibodies in synovial fluid confirms that the joint inflammation is due to Lyme disease infection. Positive results guide treatment decisions, typically involving antibiotic therapy. The 58kD protein is one of the specific markers used in immunoblot testing to confirm exposure to Borrelia burgdorferi. This test is more specific for Lyme arthritis than blood tests alone, as it detects antibodies directly in the affected joint space.
Frequently asked questions
Is this test different from a Lyme disease blood test?
Do I need to fast before this test?
How long does it take to get results?
What happens if my test is positive?
Can I have Lyme arthritis without a positive blood test?
Sources
- 1
- 2
- 3
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.
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