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IgG Antibody to Borrelia burgdorferi (Serum)

Published: August 9, 2026Updated: August 15, 2026

This test measures the level of Immunoglobulin G (IgG) antibodies against *Borrelia burgdorferi*, the bacterium responsible for Lyme disease. These antibodies develop after infection and can help confirm a past or current Lyme disease diagnosis.

Quick summary

["IgG antibodies may indicate past or ongoing Lyme disease exposure."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 15, 2026Editorial policy

Key facts at a glance

LOINC
43928-1
Short code
COXQFM
Synonyms
C burnet Ph2 IgM Ser Ql IF
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or red-top tube without anticoagulant
Units
N/A
Ref low
0
Ref high
1
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Immunofluorescence Assay (IFA)
CPT
86638
SNOMED
12211000175109
Specimen volume
1–2 mL serum (minimum 0.5 mL)
Stability
Serum stable at room temperature for 24 hours; refrigerated (2–8°C) for 7 days; frozen (-20°C or below) for up to 6 months. Avoid repeated freeze-thaw cycles.
Hemolysis max
200
Lipemia max
100
Icterus max
40
TAT
48–120 hours
Order
routine

What Does This Test Measure?

IgG antibodies are a type of immune protein your body produces in response to *Borrelia burgdorferi* infection. These antibodies can stay in your system for months or years after the initial infection, even if symptoms have resolved. The test detects these antibodies to help diagnose Lyme disease, especially in cases where early symptoms are unclear or have improved.

Why Might You Need This Test?

Your healthcare provider may order this test if you have symptoms of Lyme disease, such as a bull’s-eye rash (erythema migrans), joint pain, fatigue, or neurological issues. It may also be used to check for past infection if you’ve lived in or traveled to areas with high Lyme risk, even if you don’t currently have symptoms.

When Might You Get False Results?

While IgG tests are generally reliable, they may not detect early Lyme disease (when antibodies haven’t yet formed). Additionally, some people with past infections may have lingering antibodies that don’t always reflect active disease. False positives can sometimes occur with other infections or autoimmune conditions, though this is rare.

What to Expect During the Test

A blood sample will be drawn from a vein in your arm. The sample is sent to a lab for testing. Results are typically ready within a few days to a week, depending on the lab.

Reference range

Negative: <1:16; Equivocal: 1:16–1:32; Positive: ≥1:64. Phase 2 IgM antibodies indicate acute or recent infection with Coxiella burnetii (Q fever).N/A

Specimen: serum

No special preparation required. Specimen should be collected prior to administration of antibiotics when possible to maximize diagnostic yield. Acute and convalescent samples (2–4 weeks apart) are recommended for seroconversion confirmation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Anti-Lyme Antibody

Frequently asked questions

Is this test used to diagnose Lyme disease right away?
No. Early Lyme disease is often diagnosed using a combination of clinical symptoms, physical exam findings, and sometimes a different test called the *IgM antibody test* (which detects newer antibodies). IgG tests are more useful for confirming past infection or monitoring chronic symptoms.
Can this test help me if I’ve already been treated for Lyme disease?
Yes. IgG tests can help assess whether your body has cleared the infection or if residual antibodies suggest lingering immune activity. This may guide decisions about retreatment or further testing.
What if my test results are positive but I don’t have symptoms?
A positive IgG test alone doesn’t always mean active Lyme disease. Your healthcare provider will consider your medical history, symptoms, and other test results to determine if further evaluation or treatment is needed.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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 15, 2026. · Read our editorial policy