Lyme Western Blot Test
$89.00
Second-tier Lyme disease Line Blot testing for IgG and IgM antibodies to specific Borrelia burgdorferi proteins. Intended primarily after a positive or equivocal Lyme EIA, ELISA or IFA. If you have not yet had initial Lyme antibody screening, order the complete Lyme Antibodies with Reflex profile instead.
Description
The Lyme Disease Line Blot is a second-tier confirmatory antibody test for Borrelia burgdorferi, the primary bacterium responsible for Lyme disease in the United States.
This test is intended primarily for people who have already had a Lyme ELISA, EIA or IFA screening test that was reported as positive or equivocal but still need the confirmatory portion of standard two-tier testing.
The test evaluates both IgM- and IgG-specific antibody responses against individual Borrelia burgdorferi proteins.
Labcorp Test 163600 – Lyme Disease, Line Blot
Have You Not Been Tested for Lyme Disease Yet?
If you are starting the Lyme evaluation from the beginning, this standalone Line Blot is generally not the preferred first test.
Instead, order the Lyme Disease Antibodies, Total and IgM with Reflex to Line Blot.
That profile starts with the initial antibody screen and automatically performs the more specific confirmatory testing when the screening result meets the laboratory criteria for reflex testing.
View the Complete Lyme Antibody + Reflex TestWhat Is the Lyme Disease Line Blot?
The Lyme Line Blot is an antibody test that evaluates immune reactivity against a defined set of proteins from Borrelia burgdorferi.
This is the laboratory method Labcorp currently uses for test 163600. The term Western blot is still commonly used by patients and clinicians because immunoblot testing has historically served as the second step of conventional Lyme serology.
Rather than simply reporting an overall antibody signal, the Line Blot examines whether IgM or IgG antibodies react with specific Borrelia antigens.
Why Is This a Second-Tier Lyme Test?
Lyme serology traditionally uses a two-step approach.
Initial Screen
An EIA, ELISA or similar immunoassay looks broadly for antibodies against Borrelia burgdorferi.
Positive or Equivocal
A reactive first-tier result triggers more specific second-tier antibody testing.
Line Blot
IgM and IgG responses to individual Borrelia proteins are evaluated according to established interpretation criteria.
The first-tier immunoassay provides sensitivity, while the second-tier test improves specificity and helps reduce false-positive interpretation from nonspecific antibody reactions.
Line Blot vs Lyme Antibodies With Reflex: Which Test Should I Order?
| Test | Best Used For | What It Does |
|---|---|---|
| Lyme Antibodies, Total and IgM With Reflex to Line Blot | Most patients beginning a Lyme disease evaluation | Performs initial Lyme antibody screening and reflexes to more specific testing when the first result is positive or equivocal. |
| Lyme Disease Line Blot – Test 163600 | Patients who already had a positive or equivocal first-tier Lyme screen but did not receive the appropriate second-tier test | Evaluates IgG and IgM antibodies against specific Borrelia burgdorferi proteins. |
What Does the Lyme Line Blot Detect?
The Line Blot identifies antibody responses against specific proteins associated with Borrelia burgdorferi.
Early Immune Response
IgM antibodies generally develop earlier in infection. IgM results have their greatest diagnostic relevance during the first several weeks after symptom onset.
Established Immune Response
IgG develops later and typically becomes the more important antibody response as the duration of infection increases.
Important: IgM Is Interpreted Differently After 30 Days
One of the most important issues in Lyme testing is the duration of symptoms.
IgM + IgG
During the first 30 days of symptoms, both IgM and IgG immunoblot results may provide useful diagnostic information.
IgG Becomes More Important
After approximately 30 days of illness, IgG should generally be used for serologic interpretation. Continuing to rely on isolated IgM positivity increases the risk of false-positive diagnosis.
Does the Line Blot Tell How Long You Have Had Lyme Disease?
Not precisely.
The older description of IgM as “early Lyme” and IgG as “late Lyme” is useful as a general concept but can be misleading if interpreted too literally.
Antibody responses vary among individuals, and IgG antibodies may remain detectable long after infection has been treated.
The Line Blot therefore provides evidence of an immune response to Borrelia burgdorferi; it does not function as a clock that determines exactly when infection began.
What Does a Positive Lyme IgG Mean?
Positive Lyme IgG indicates that the immune system has developed a sufficiently characteristic antibody response to Borrelia burgdorferi under the laboratory's interpretation criteria.
The result must still be interpreted with:
- Current symptoms
- Duration of illness
- Geographic exposure
- History of tick exposure
- Possible erythema migrans rash
- Previous Lyme diagnosis or treatment
- Other clinical findings
IgG antibodies may remain positive for years and should not be used by themselves to determine whether treatment was successful.
Why Can the Initial Lyme Screening Test Be Positive When the Line Blot Is Negative?
First-tier Lyme immunoassays are designed to identify potentially reactive samples. However, antibodies produced during other infections or immune conditions can occasionally react with components of a screening assay.
The second-tier test evaluates a more specific pattern of antibody responses against individual Borrelia proteins.
This is one reason two-tier testing improves diagnostic specificity.
Can the Line Blot Be Negative in Early Lyme Disease?
Yes.
Lyme antibody testing depends on the immune system having enough time to develop a detectable antibody response.
During the earliest stage of infection, serologic testing may still be negative even when Lyme disease is present.
Symptoms That May Lead to Lyme Disease Testing
Early Infection
- Erythema migrans rash
- Fever or chills
- Headache
- Fatigue
- Muscle aches
- Joint discomfort
- Swollen lymph nodes
Disseminated Disease
- Multiple skin lesions
- Facial nerve palsy
- Meningitis symptoms
- Radicular pain
- Palpitations
- Lyme carditis
Later Manifestations
- Recurrent or persistent large-joint swelling
- Lyme arthritis
- Selected neurologic manifestations
What the Lyme Line Blot Cannot Tell You
- Exactly when infection occurred
- Whether every current symptom is caused by Lyme disease
- Whether viable bacteria remain after treatment
- Whether treatment has been successful based solely on antibody persistence
- Whether a negative very-early antibody test completely excludes Lyme disease
When Is the Standalone Lyme Line Blot Most Useful?
This test is most appropriate when:
- You already had a positive Lyme ELISA, EIA or IFA performed elsewhere.
- Your previous Lyme screening result was equivocal.
- The original laboratory did not automatically perform second-tier testing.
- Your physician needs the IgG and IgM Line Blot portion to complete a conventional two-tier evaluation.
Starting From Scratch?
You usually do not need to order the standalone Line Blot first.
The Lyme Disease Antibodies, Total and IgM with Reflex to Line Blot is designed to begin with the screening step and proceed to confirmatory testing automatically when required.
Labcorp Lyme Disease Line Blot
- Labcorp test number: 163600
- Method: Line blot
- Specimen: Serum
- Includes: IgG and IgM Line Blot analysis and interpretation
- Typical turnaround: approximately 1–5 days
- Preparation: No special fasting is generally required
Frequently Asked Questions
Is a Lyme Line Blot the same as a Western blot?
They are related immunoblot approaches, and “Western blot” remains a familiar term in Lyme testing. Labcorp currently identifies test 163600 specifically as a Lyme Disease Line Blot.
Should I order this test if I have never been tested for Lyme disease?
Usually no. Initial Lyme evaluation should generally begin with an appropriate first-tier antibody assay. The Lyme Antibodies with Reflex profile performs that screening step and adds confirmatory testing when indicated.
Why does the other Lyme test cost more?
The complete Lyme antibody profile includes the initial antibody screening process and can reflex to the more specific second-tier test when required. This standalone Line Blot represents only the second-tier portion of that diagnostic sequence.
Does positive IgM mean I have active Lyme disease?
Not necessarily. IgM is most useful during the first 30 days after symptom onset. Isolated IgM reactivity later in the illness carries a greater risk of false-positive interpretation.
Does positive IgG mean Lyme disease is still active?
No. IgG can persist for many years after infection and may remain positive following successful treatment. Results must be interpreted with symptoms and clinical history.
Can a Lyme blood test be negative early in infection?
Yes. Antibodies take time to develop. Testing during the earliest stage of infection can therefore be negative despite infection.
Does a negative Line Blot completely rule out Lyme disease?
No. Timing, previous treatment, immune response and the clinical presentation all matter. The Line Blot is also intended to be interpreted as part of a two-tier testing strategy rather than as an isolated screening test.
Can the Line Blot determine whether Lyme treatment worked?
No. Lyme antibodies can remain detectable long after treatment, so repeat antibody testing is generally not a reliable test of bacterial eradication or treatment success.