How do you read QuantiFERON gold results?

How are QFT-Plus results interpreted?

1. Positive – suggests that TB infection is likely.
2. Negative – suggests that TB infection is unlikely.
3. Indeterminate – suggests the need for further investigations or repeat testing.

What is QuantiFERON TB Gold In Tube test?

QuantiFERON-TB Gold (QFT) is a simple blood test that aids in the detection of Mycobacterium tuberculosis, the bacteria which causes tuberculosis (TB). QFT is an interferon-gamma (IFN-γ) release assay, commonly known as an IGRA, and is a modern alternative to the tuberculin skin test (TST, PPD or Mantoux).

What happens if QuantiFERON Gold test is positive?

Most people with a positive TB blood test have latent TB infection. To be sure, your doctor will examine you and do a chest x-ray. You may need other tests to see if you have latent TB infection or active TB disease.

What is a normal QuantiFERON TB Gold?

Conclusions. We recommend retesting of subjects with QFT results in the range 0.20–0.99 IU/ml to enhance reliability and validity of the test. Half of the subjects in the borderline range will be negative at a level <0.20 IU/ml when retested and have a very low risk of developing incident active TB.

What is a normal QuantiFERON mitogen value?

How reliable is TB Gold test?

The overall sensitivity for active TB was 87.5%, ranging from 62.5% in children 25–36 months old to 100% in children older than 49 months. The overall specificity for active TB was 93.6%. Among the 481 children tested for LTBI screening, 38 scored positive and all but 2 had at least one risk factor for TB infection.

Can a positive TB blood test be wrong?

The test might show you don’t have TB when you do, especially if you were exposed a long time ago and your immune response to it is weak. Or you could get a false positive result if you’ve been vaccinated with the TB bacillus Calmette-Guerin (BCG) vaccine.

What is TB mitogen?

The mitogen tube also serves as a control for indicating long or improper transport, incorrect blood handling and incubation. If technical issues are suspected with the collection or handling of blood samples, repeat the entire QuantiFERON TB Gold Plus test with new blood specimens.

Is QuantiFERON positive in latent TB?

You have a positive Tuberculin Skin Test (TST) or QuantiFERON blood test: what does this mean? If your TST (Mantoux) or Quantiferon blood test was found to be positive, this means you have a latent TB infection, but usually not the active disease.

What is the QuantiFERON®-TB Gold test?

On May 2, 2005, a new in vitro test, QuantiFERON®-TB Gold (QFT-G, Cellestis Limited, Carnegie, Victoria, Australia), received final approval from the U.S. Food and Drug Administration as an aid for diagnosing Mycobacterium tuberculosis infection.

How are QFT results interpreted for the diagnosis of Mycoplasma tuberculosis?

Interpretation of QFT results ( Table 2) is stratified by estimated risk for infection with M. tuberculosis, in a manner similar to that used for interpreting TST with different cut-off values. QFT results indicative of M. tuberculosis infection include the following three criteria: (mitogen — nil) and (tuberculin — nil) are both > 1.5 IU; and

What is the percentage tuberculin response cut-off for interpreting QFT tests?

Using 30 as the percentage tuberculin response cut-off for interpreting a QFT test as positive identifies approximately the same number of persons compared with using a TST induration cut-off of 15 mm. The test is considered negative if (mitogen — nil) >1.5 IU but (tuberculin — nil) < 15% (mitogen — nil).

Is QFT-G more specific for tuberculosis than tuberculin purified protein derivative?

Because these proteins are absent from all Bacille Calmette-Guérin (BCG) vaccine strains and from commonly encountered nontuberculous mycobacteria (NTM) except M. kansasii, M. szulgai, and M. marinum ( 1 ), QFT-G is expected to be more specific for M. tuberculosis than tests that use tuberculin purified protein derivative (PPD) as the antigen.