Mycobacterium tuberculosis Antigen Detection (Serum/Plasma)
This test checks for the presence of Mycobacterium tuberculosis antigens in your blood, which may indicate an active tuberculosis (TB) infection.
["Helps diagnose TB by detecting specific proteins from the bacteria in your bloodstream."]
Key facts at a glance
- LOINC
- 76687-3
- Short code
- Mycobacterium BAL Cult
- Synonyms
- Mycobacterium BAL Cult
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- organism-specific-culture
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What This Test Measures
The test identifies Mycobacterium tuberculosis antigens—specific proteins produced by the bacteria that cause TB. These proteins are released into your blood when the infection is active. This method helps confirm TB before symptoms appear or when other tests are inconclusive.
Why It Might Be Ordered
Your healthcare provider may order this test if you have symptoms of TB (such as fever, cough, or weight loss), if you’ve been exposed to TB, or if you have a weakened immune system. It’s also used in screening for TB in certain high-risk groups.
How the Test Works
Blood is drawn and analyzed using an immunoassay (a lab test that detects specific proteins) to detect the presence of TB antigens. The result is qualitative, meaning it only tells whether the antigens are present or not.
What to Expect Before the Test
No special preparation is needed. You may have a slight bruise or soreness at the injection site, but this is normal. Avoid alcohol or certain medications (like blood thinners) before the test if instructed by your provider.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A positive result strongly suggests an active TB infection and should prompt immediate medical evaluation and treatment. A negative result means no detectable antigens were found, but TB could still be present in early or latent stages. Follow-up testing or additional evaluations may be needed based on clinical findings and exposure history.
Short name
TB Antigen Test
Frequently asked questions
How long does it take to get results?
What does a positive result mean?
Can this test detect latent TB?
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