IgM Antibody to Mycobacterium tuberculosis (Serum or Plasma)
This test measures the presence of IgM antibodies in your blood, which may indicate an active or recent infection with *Mycobacterium tuberculosis* (the bacterium responsible for tuberculosis). IgM is one of the first antibodies produced when your immune system encounters the infection.
["IgM antibodies can help identify if you’ve recently been exposed to TB or if the infection is still active."]
Key facts at a glance
- LOINC
- 109528-0
- Short code
- IgM Msmt BldCo
- Synonyms
- IgM Msmt BldCo
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82784
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What Does This Test Measure?
IgM antibodies are part of your immune system’s immediate response to infection. When your body detects *Mycobacterium tuberculosis*, it produces these antibodies quickly to fight the germ. This test checks for their presence in your serum or plasma, which can signal recent exposure or an ongoing infection.
Why Might You Need This Test?
Doctors may order this test if you have symptoms of TB (such as coughing, fever, or weight loss), a history of exposure to TB, or if you live in an area with higher TB rates. It can also help confirm a diagnosis when other tests are inconclusive.
What to Expect Before the Test
No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw a blood sample. If you’re nervous, let your healthcare provider know—they can help make it more comfortable.
What to Expect After the Test
After the blood is drawn, you’ll likely feel a brief pinch or pressure. Most people recover quickly, but some may experience mild bruising or soreness. Avoid vigorous activity for a few hours to prevent bruising.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
IgM antibodies to *Mycobacterium tuberculosis* can appear within weeks to months after infection. While they’re useful for detecting recent exposure, they’re less reliable for diagnosing chronic or latent TB compared to other tests (like IgG or culture). A positive result suggests active infection or recent exposure, but further testing (such as a TB skin test or culture) may be needed for confirmation.
Short name
IgM TB Antibody
Frequently asked questions
When Might I Get False Results?
How Long Does It Take to Get Results?
Can I Take This Test at Home?
Sources
- 1
- 2Lab Tests OnlineSource
- 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