QuantiFERON Test

QuantiFERON Test information


Updated June 25, 2017 By

What is the QuantiFERON Test?

The QuantiFERON test is a blood test that is used to screen for latent tuberculosis.

Is the QuantiFERON Test approved by the FDA?

Yes. The QuantiFERON test was approved by the FDA in 2001.

How does the QuantiFERON test work?

The QuantiFERON Test is a type of Interferon-Gamma Release Assay, or IGRA, test. This test helps check for the presence of a response to Mycobacterium tuberculosis.

What does the QuantiFERON test look for?

The QuantiFERON test helps detect the presence of latent Mycobacterium tuberculosis infections.

Why was the QuantiFERON test developed?

Historically, the tuberculosis skin test (also known as the TB skin test and TST test) was the gold standard for looking for the presence of latent TB. The TB skin test requires one injection and one reading by a medical provider 48-72 hours later. Unfortunately, the TB skin test is not only inconvenient because it requires two visits but it also has significant limitations when the patient has a weakened immune system or is from another country and has received the (Bacille-Calmette-Guerin) BCG vaccine. As a result, the QuantiFERON test was developed to address these issues.

Why do people need to be screened for tuberculosis?

Tuberculosis testing is performed on people who are going to be studying or working in settings in which a lot of different people will be interacting. Examples of settings like that include schools (both teachers and students), volunteer organizations, and healthcare settings. The rare person that has active tuberculosis (in particular, tuberculosis in the lungs) can easily spread it to anyone they talk to, touch or interact with. The QuantiFERON test is one form of tuberculosis screening that helps identify those rare cases and prevent active spreading when people are interacting in groups.

Why do people get the QuantiFERON test?

Many people test positive for tuberculosis on the standard medical skin test. Unfortunately, there is a high rate of false positives, usually because of prior vaccination with the BCG vaccine administered for tuberculosis protection. Until the advent of blood tests like the QuantiFERON test, people with a positive TB skin test who needed TB clearance would be required to get a chest x-ray (often annually).

What are other advantages to the QuantiFERON test?

The QuantiFERON test only requires a single visit whereas a PPD, also known as a TB skin test, requires 2 visits (placement and read). Depending on the lab, results for the QuantiFERON test can often be obtained in 48 hours.

What are disadvantages of a QuantiFERON test?

The test requires a blood draw. Also, the blood has to be handled in a special way or else the QuantiFERON test has to be repeated. Finally, acceptance of this test is not fully mainstream yet although acceptance is increasing.

Do I have to fast before a QuantiFERON test?

No fasting is required for the test.

What is the procedure for getting a QuantiFERON test?

The best way to get a QuantiFERON test is to find a lab in your area that specifically offers QuantiFERON testing as it is a specialized test. Then, make an appointment fo your test and get your blood drawn.

What happens to my blood after it is drawn for the QuantiFERON test?

Blood drawn for the QuantiFERON test has to be processed using a special machine to prepare your sample.

How long does it take to get QuantiFERON test results?

QuantiFERON test results typically take longer than most other types of blood tests. The average QuantiFERON test result takes 6 business days but sometimes the report can come back sooner (depending on the lab and the turnaround time of the medical provider who ordered the test).

How do I interpret QuantiFERON test results?

Here is a helpful video for interpreting your results:

What does a negative QuantiFERON test result mean?

A negative QuantiFERON test means that there is no evidence of latent TB.

What does an equivocal QuantiFERON test result mean?

An equivocal QuantiFERON test usually means that the test was unable to tell if latent TB exists and requires following the same protocol as if the test was positive. In rare cases, an equivocal QuantiFERON test result means that something went wrong during the processing of the blood and that the test needs to be repeated.

What does a positive QuantiFERON test result mean?

A positive QuantiFERON test is the same as a positive TB skin test - that latent tuberculosis most likely exists in the person. The next step would be to get a chest x-ray or similar imaging study to make sure that the person who got tested does not have active tuberculosis (i.e. tuberculosis evidence in the lungs) as that is a public health emergency.

How much does a QuantiFERON test cost?

The cost of the QuantiFERON test ranges widely. Test costs can range from $150 to $500+.

Do I need to prepare in any special way for a QuantiFERON test?

No, and fasting is not required.

Will my insurance cover a QuantiFERON test?

It depends on your insurance. Some insurance plans cover it while other people order the QuantiFERON test online.

I also need other titer tests. What does that mean?

Titer tests are blood tests that are frequently ordered with the QuantiFERON test. Proof of immunity through a titer test is often required by work or school in conjunction with your TB clearance from the QuantiFERON test.

We hope that you found our QuantiFERON test information helpful.