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Immunoglobulin M (IgM) Antibody to Mycoplasma pneumoniae

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

This test measures antibodies in your blood that your immune system produces in response to an infection caused by *Mycoplasma pneumoniae*, a common bacterial cause of respiratory infections like pneumonia.

Quick summary

["Detects past or recent infection by *Mycoplasma pneumoniae* through antibody presence."]

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

Key facts at a glance

LOINC
56123-3
Short code
IgM Ur-mCnc
Synonyms
IgM Ur-mCnc
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What This Test Measures

IgM antibodies are part of your immune system’s immediate response to infection. They appear early in the course of a *Mycoplasma pneumoniae* infection and can help identify if you’ve been recently exposed to this bacterium.

Why It’s Done

Your healthcare provider may order this test if you have symptoms like persistent cough, fever, or chest pain that suggest *Mycoplasma pneumoniae* infection, especially if other tests (like a throat culture) are inconclusive.

When Results May Be Positive

Results may be positive within days to weeks after infection, depending on how your immune system reacts. IgM levels typically decline as your body clears the infection, but they may remain detectable for months.

Limitations and Considerations

This test cannot confirm a *Mycoplasma pneumoniae* infection definitively on its own. It may also show false positives if you’ve been exposed to other bacteria or have an unrelated immune response. Always discuss results with your doctor.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgM Anti-Mycoplasma pneumoniae is useful for diagnosing suspected respiratory infections when other tests are unavailable or inconclusive. It helps differentiate *Mycoplasma pneumoniae* from viral or other bacterial causes of similar symptoms, guiding appropriate treatment decisions.

Short name

IgM Anti-Mycoplasma pneumoniae

Frequently asked questions

When might I get false-positive or false-negative results?
False positives can occur if you’ve been exposed to other bacteria or have an unrelated immune response. False negatives may happen if the test is taken too early (before IgM antibodies develop) or too late (after IgM levels drop). Your doctor will consider timing and clinical symptoms when interpreting results.
How long does it take to get results?
Results are typically available within 24 to 48 hours of testing, depending on your lab’s processing time. Your doctor will contact you once results are ready.
Does this test require fasting?
No fasting is required for this blood test. You may eat and drink normally before the draw.
  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