Tuberculosis (TB) Testing — Last 7 Days
This label refers to a TB test or TB-related finding recorded within the previous 7 days. It does not identify a specific specimen or testing method.
["A recent TB result may help determine whether you have been exposed to TB or have active tuberculosis, but interpretation depends on the type of test and timing."]
Key facts at a glance
- LOINC
- 54792-7
- Short code
- TUBERCULOSISINLAST7D
- Synonyms
- —
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- mdsv
- CPT
- 84484
- SNOMED
- 302774002
- 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 is this test?
Tuberculosis testing is used to determine whether a person has been exposed to TB bacteria or has active TB disease. The wording “last 7 days” indicates a time window for a test result or related record; it does not specify whether a skin test, blood test, or respiratory specimen test was performed.
Why might I need this test?
TB testing may be ordered after close contact with someone who has TB, when symptoms suggest TB, or as part of screening in healthcare, childcare, or other settings. A recent result can be especially important when assessing possible exposure.
How is the test performed?
Depending on the test, a small amount of blood may be drawn for an interferon-gamma release assay, or a skin-prick test may be used. Tests for active TB usually examine a respiratory sample with a nucleic acid amplification test, culture, or another laboratory method.
How do I prepare for the test?
Blood-based TB tests generally do not require fasting. A respiratory test may require you to cough up sputum, and you may be given instructions about mask use and avoiding food or drinks beforehand. Follow the specific preparation instructions provided by your healthcare professional.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A positive immune-based TB test usually indicates infection with TB bacteria but does not by itself show that active TB disease is present. A positive nucleic acid amplification test or culture may be more consistent with active TB. A negative result does not always exclude TB, especially when exposure or symptoms occurred recently, so your clinician may recommend additional testing based on your circumstances.
Short name
Recent TB test
Frequently asked questions
Does a positive TB test mean I have active tuberculosis?
Are the TB skin test and TB blood test the same?
What should I do if I had a negative TB test but was recently exposed?
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 17, 2026. · Read our editorial policy