Skip to content

IgM Antibody to Borrelia burgdorferi (Lyme Disease) by Immunoassay

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

This test measures the presence of IgM antibodies against *Borrelia burgdorferi*, the bacterium responsible for Lyme disease. These antibodies develop in your blood after infection and can help confirm an active or recent Lyme infection.

Quick summary

["This test helps diagnose Lyme disease by detecting immune system responses to the Lyme bacterium."]

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

Key facts at a glance

LOINC
111304-2
Short code
COXPH2M
Synonyms
C burnet Ph2 IgM Msmt Ser
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or red-top vacutainer tube
Units
N/A
Ref low
16
Ref high
1
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Enzyme-linked immunosorbent assay (ELISA) or Indirect Immunofluorescence Assay (IFA) for detection of IgM antibodies against Coxiella burnetii phase 2 antigen
CPT
86638
SNOMED
395124008
Specimen volume
1-2 mL of serum
Stability
Stable at 2-8°C for 7 days; for longer storage, freeze at -20°C or below; avoid repeated freeze-thaw cycles
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
24–72 hours
Order
routine

What Does This Test Measure?

The test detects IgM antibodies, a type of immune protein your body produces in response to infection. These antibodies appear shortly after infection and can persist for months or years. The test is used to identify if you have an active or recent Lyme infection, though results can vary based on timing since exposure.

How Is the Sample Collected?

A blood sample is drawn from a vein in your arm by a healthcare professional. The blood is processed to separate the serum, where the test is performed.

Why Might This Test Be Ordered?

Your healthcare provider may order this test if you have symptoms like fever, fatigue, rash (e.g., bull’s-eye rash), joint pain, or neurological issues that align with Lyme disease. It’s also used in follow-up testing for suspected Lyme after initial negative results or in cases of persistent symptoms.

What Are Common Symptoms of Lyme Disease?

Lyme disease often starts with a red rash (erythema migrans) at the bite site, followed by flu-like symptoms such as fever, chills, headache, and fatigue. Joint pain, muscle aches, or neurological symptoms (e.g., numbness, memory issues) may also occur later. Symptoms can vary widely and may not always appear immediately.

Reference range

Negative: <1:16 (IFA) or <9 U/mL (ELISA); Equivocal: 1:16-1:32 (IFA) or 9-11 U/mL (ELISA); Positive: >1:32 (IFA) or >11 U/mL (ELISA). Phase 2 IgM antibodies indicate acute Q fever infection.N/A

Specimen: serum

No fasting required. Patients should inform their healthcare provider of any recent antibiotic use, as early antibiotic therapy may blunt the antibody response. Acute-phase specimens should be collected 2-3 weeks after symptom onset for optimal sensitivity.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgM Lyme Antibody

Frequently asked questions

When will I get my results back?
Results are typically available within 1–3 business days, depending on lab processing times. Your healthcare provider will discuss the results with you, including any follow-up testing or treatment plans.
Can I have this test if I’ve already been treated for Lyme?
Yes, your provider may order this test if you have lingering symptoms (e.g., fatigue, joint pain) after treatment or if you suspect a relapse. Antibody levels can sometimes remain detectable even after treatment, so results should be reviewed with your doctor.
What if my test is positive but I don’t have symptoms?
A positive IgM result suggests recent exposure to *Borrelia burgdorferi*, but symptoms may not appear for weeks or months. If you’re asymptomatic, your provider may recommend monitoring or additional testing to assess risk. False positives can rarely occur, so clinical correlation is key.
  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 16, 2026. · Read our editorial policy