Lab test · Infection
TB Interferon-Gamma Release Assay (IGRA)
Tuberculosis (TB) infection
- Blood sample
- No fasting
- Report within 4 days
- Home collection
What this test is for
Tuberculosis (TB) infection
The IGRA is a blood test that shows whether your immune system has met the bacteria that cause tuberculosis (TB). White blood cells in the sample are exposed to TB proteins, and if you have been infected they release a substance called interferon-gamma, which is measured. It detects TB infection, including inactive (latent) infection, but it cannot tell latent infection from active TB disease. Unlike the skin test, it is not affected by the BCG vaccine.
Why a doctor may order it
- After close contact with someone who has active TB
- Before starting medicines that weaken the immune system, such as some treatments for arthritis
- In people with HIV or other conditions that lower immunity
- As screening for health workers or before some jobs or travel
- To help assess possible TB alongside other tests
How to prepare
Fasting: Not needed.
You can eat and drink as usual; no preparation is needed. Tell your doctor about any medicines or conditions that weaken the immune system, such as steroids, as they can affect the result.
At home
- Sample
- Blood sample
- How it works
- The collector takes a blood sample from a vein in your arm into the special tubes this test needs and handles them as the laboratory requires. The draw takes a few minutes.
- Report
- Within 4 days of collection.
What the results can mean
A positive result means you have been infected with TB bacteria at some time. It does not show whether the infection is active, so your doctor may arrange a chest X-ray and sputum tests. A negative result makes TB infection unlikely, but it can be falsely negative in people with a weak immune system or a very recent infection. An indeterminate result may need a repeat test. Your doctor will interpret the result for you.
What's included
One test: TB Interferon-Gamma Release Assay (IGRA), from one blood sample.
Related tests
- HIV 1 and 2 Antibody TestThis blood test screens for antibodies to HIV-1 and HIV-2, the two types of human immunodeficiency virus.
- Complete Blood Count (CBC)A complete blood count looks at the three main types of cells in your blood: red blood cells, which carry oxygen; white blood cells, which fight infection; and platelets, which help blood to clot.
- Erythrocyte Sedimentation Rate (ESR)The ESR measures how quickly red blood cells settle to the bottom of a tall, thin tube over a set time.
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Questions people ask
What is the difference between an IGRA and the Mantoux skin test?
Both check for TB infection. The IGRA needs only one blood sample and is not affected by the BCG vaccine, while the skin test needs a second visit to read the reaction and can be positive after BCG.
Does a positive IGRA mean I have active TB?
No. It shows TB infection, which may be latent. Your doctor will check for symptoms and may order a chest X-ray and sputum tests to look for active disease.
What is latent TB?
Latent TB means the bacteria are in the body but inactive. People with latent TB have no symptoms and cannot spread it, but it can become active later, so doctors sometimes recommend treatment.
How much does a TB IGRA test cost in Dhaka?
With Mukti Health the price is ৳4,920, and the sample is collected at your home in Dhaka. You see the price again before you confirm the booking in the Mukti Health app.
Can I do the TB IGRA test at home in Dhaka?
Yes. Book it in the Mukti Health app and a trained sample collector comes to your home in Dhaka to take the blood sample. You do not need to go to a laboratory.
How long does the TB IGRA report take?
The report is usually ready within 4 days of the sample being collected.