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Tuberculosis

Quantiferon TB Gold Blood Test

02/10/2009

Question:

By having a history of +ppd x 10years, would the blood test be necessary? The blood test is now offered where I work. INH was taken. Chest x ray normal.

Answer:

If you have had a positive tuberculin skin test or PPD in the past and completed latent TB infection treatment with isoniazid (INH) there is NO need for the QuantiFERON TB blood test. If you need serial or annual tuberculosis (TB) screening for work, you will need to continue to fill out the TB screening risk assessment for any signs or symptoms of active TB disease as per your institution’s employment protocol.

Currently there are two Interferon gamma release assays (IGRA) approved by the Food and Drug Administration (FDA) for the diagnosis of latent TB infection: The QuantiFERON-TB Gold Test and the TSpot TB Test. These blood tests measure the response to TB proteins when they are mixed with a small amount of blood.

The Centers for Control and Prevention (CDC) published a guideline for the TB blood test in Morbidity and Mortality Weekly Report in December 2005. An updated guideline is anticipated to be released soon. You can use an IGRA in anyone you would use the TST, however data are still lacking in several clinical circumstances including severely immunocompromised patients, patients at the extremes of age, and groups receiving periodic screening.

Related Resources:

Guidelines for Using the QuantiFERON®-TB Gold Test for
Detecting Mycobacterium tuberculosis Infection, United States

For more information:

Go to the Tuberculosis health topic, where you can:

Response by:

Shu-Hua   Wang, MD, MPH&TM Shu-Hua Wang, MD, MPH&TM
Clinical Assistant Professor of Infectious Diseases
Clinical Assistant Professor of The Division of Epidemiology
College of Medicine
The Ohio State University

Larry S Schlesinger, MD Larry S Schlesinger, MD
Professor:
Molecular Virology, Immunology and Medical Genetics
Microbiology Administration
Environmental Health Sciences
College of Medicine
The Ohio State University