QuantiFERON blood test for TB
QuantiFERON test · T-SPOT · TB blood test · IGRA test · interferon gamma release assay
This is a blood test from a vein. It shows if your body has met the germ that causes tuberculosis.
Instead of or together with a TB skin test, before some treatments, after contact with someone with TB, or for work or school.
⏱ Duration: the blood draw takes 3 to 5 minutes; results usually come in 2 to 7 days
Be sure to tell your doctor
How to prepare
- Food. Usually fasting, or a few hours after a light meal. Check with the lab.
- Medicines. Do not stop them on your own. Tell your doctor what you take. They will decide.
- Clothing. Wear a sleeve that is easy to roll up above the elbow.
What to bring
- Your test request form
- Your ID
- Past TB test results, if you have them
How it goes
- You sit down and rest your arm on the armrest
- A band is tightened above your elbow
- The skin is wiped with antiseptic
- Blood is drawn into several special tubes
- The needle comes out, and a cotton pad is pressed on the spot
What you'll feel
- A quick prick, like a pinch
- Sometimes slight dizziness. Tell the nurse
Afterwards
- Press the cotton pad for 3 to 5 minutes
- Results usually come in 2 to 7 days
- A positive result does not mean you are ill. A TB specialist will decide what is next
Common questions
Why is this test better than a skin test?
It is not affected by the BCG vaccine, and you do not need to come back to have your arm checked.
If the test is positive, am I contagious?
Not necessarily. The test shows contact with the germ. Other tests show whether it is active disease.