An IGRA TB test, or Interferon-Gamma Release Assay, is a blood test used to detect tuberculosis (TB) infection. It assesses the body's immune response to TB bacteria, aiding in the diagnosis of latent TB infection or active TB disease.
IGRA TB Test
Here are the basic details of the IGRA TB Test.
| Also Known As |
TB Blood Test |
| Type |
Blood Test |
| Purpose |
Detect TB Infection |
| Sample Type |
Blood |
| Preparation |
No specific prep |
| Fasting |
Not necessary |
| Gender |
All |
| Age Group |
All ages |
| Normal Value |
Negative |
| Reporting Time |
Within 24 hrs |
| Cost |
1500-4500 INR* |
*Price range may vary as per location, lab type, and procedure of lab test.
IGRA TB Test Means
IGRA stands for Interferon-Gamma Release Assay, which is a type of blood test.
- It is used to detect tuberculosis (TB) infection by measuring the body's immune response to the TB bacteria.
- IGRA tests are more specific than the traditional TB skin test (TST) and less likely to give false-positive results.
- They help diagnose latent TB infection (LTBI) in individuals at risk of TB, allowing for early treatment and prevention of active TB disease.
- IGRA tests are commonly used in healthcare settings and for screening individuals who have had close contact with TB patients.
- This test is crucial for TB control and prevention efforts, especially in populations at higher risk of TB exposure and infection.
IGRA TB Test Purpose
The purpose of the IGRA TB Test is to:
- Detects tuberculosis (TB) infection.
- Screens for latent TB.
- Helps diagnose active TB disease.
- Useful for individuals at risk of TB exposure.
- Provides an alternative to the tuberculin skin test.
- Helps with TB prevention and control efforts.

IGRA TB Test Preparation
Here is the basic preparation for the IGRA TB Test.
Before Test
- No special dietary or medication restrictions are necessary.
- Inform your healthcare provider about any medications or medical conditions.
- Be prepared for a blood sample to be drawn.
During Test
- A blood sample will be taken by a healthcare professional.
After Test
- You can resume your normal activities and diet immediately.
- Follow up with your healthcare provider for test results and interpretation.
IGRA TB Test Procedure
Here is the basic IGRA TB Test Procedure.
- Schedule an appointment with a healthcare provider for an IGRA TB test.
- No fasting or specific dietary restrictions are typically needed before the test.
- Arrive at the healthcare facility or laboratory for your appointment.
- A healthcare professional will draw a blood sample from a vein, typically in your arm.
- Alternatively, if the QuantiFERON-TB Gold test is used, blood is collected directly into specialized tubes.
- The blood sample is sent to a laboratory for analysis.
- Test results are usually available within a few days, and you'll receive them from your healthcare provider.
IGRA TB Test Result
IGRA TB test results are typically reported as either positive or negative.
- A positive result indicates exposure to tuberculosis infection.
- A negative result suggests the absence of current infection, but it doesn't rule out past exposure or potential future infection.
IGRA TB Test Normal Result
Here is the normal result of the IGRA TB Test.
| Test Name |
Normal Range |
| IGRA TB Test |
Negative for no immune reaction to TB bacteria |
IGRA TB Test Interpretation
Here is the Interpretation of the IGRA TB Test.
| Test Result |
Interpretation |
| Positive |
Indicates that there is an immune reaction to TB bacteria, suggesting likely TB infection. |
| Negative |
Suggests that there is no immune reaction to TB bacteria, indicating that TB infection is unlikely. |
| Uninterpretable |
The test result is inconclusive, invalid, or borderline, and further evaluation is needed. |
IGRA TB Test Positive Result
IGRA TB Test Negative Result
Specimen Requirements For IGRA TB Test
Here are the specimen requirements for the IGRA TB Test.
|
Specimen
|
Serum
|
|
Volume
|
1 ml
|
|
Container
|
Red-top tube or gel-barrier tube
|
|
Collection
|
Separate serum from cells within one hour of collection. Transfer to a plastic transport tube before shipping.
|
|
Storage
|
Refrigerate or freeze.
|
|
Sample Stability
|
Temperature
|
Period
|
|
Room temperature
|
7 day
|
|
Refrigerated
|
14 days
|
|
Frozen
|
60 days
|
|
Freeze/thaw cycles
|
Stable x1
|
|
Causes for Rejection
|
Grossly hemolyzed; bacterial contamination; lipemic specimen; icteric specimen; non-serum specimen types
|
IGRA TB Test is Safe?
- The IGRA TB test is generally considered safe and poses minimal risk to patients.
- It does not involve the use of live tuberculosis bacteria, reducing the risk of infection.
When Do You Get IGRA TB Test Results?
- IGRA TB test results are typically available within 24 hrs after the blood sample is collected.
- The exact timing may vary depending on the laboratory and healthcare facility conducting the test.
IGRA TB Test Limitation
Here is the basic limitation of IGRA TB Test.
- The IGRA TB test may produce false-positive or false-negative results in certain situations.
- It cannot differentiate between latent TB infection and active TB disease.
- Test accuracy can be affected by the person's immune status and other factors.
- IGRA testing may not be suitable for individuals with specific medical conditions or those on immunosuppressive treatments.
- A positive result does not confirm active TB but indicates potential exposure or latent infection. Clinical evaluation is needed to make a diagnosis.
IGRA TB Test Risk Factors
Here are some of the risk factors of the IGRA TB Test.
- The IGRA TB test carries minimal risk and is considered safer than the Tuberculin skin test.
- It does not cause a tuberculosis infection or active disease.
- There are no allergic reactions to test substances.
- Very rarely, some individuals may experience mild irritation at the injection site.
- The test is generally safe for pregnant women and those with weakened immune systems. However, discuss any specific health concerns with your healthcare provider.
Doctor Recommendations After IGRA TB Test Result
Here are the Doctor's recommendations or consult a specialist after the IGRA TB Test.
| IGRA TB Test Result |
Doctor to Visit |
Reason |
| High |
Pulmonologist |
Likely active tuberculosis infection |
| Normal |
No specific doctor |
Results within normal range |
| Low |
General Practitioner |
Potential past TB exposure or other issues |
IGRA TB Test Price
Here are the estimated IGRA TB Test Prices in India with different top cities:
*Prices are approximate and vary depending on a specific laboratory or healthcare facility.
Summary
Overall, IGRA TB Test is essential for detecting latent tuberculosis infection, aiding in early intervention and preventing the spread of active TB. Also check Drlogy Test for detailed information about all medical tests for patients, doctors, scholers and medical students.
Reference
- IGRA TB Test - Wikipedia [1].
- IGRA TB Test - NIH [2].