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Results of TB Tests



Why do TB tests sometimes have a response with redness and swelling, and pustules after the three day time limit for accurately reading the test, and what should be done about it?


It is not know why some patients have a delayed response to the PPD. The interpretation of this delayed reaction is usually individualized. It is important for the patient to be seen by their health care provider to evaluate and measure the reaction. If the reaction appears to be truly indurated then it is generally interpreted as real or positive if it is large enough. With the new availability of the interferon gamma release assays we have a good second test to confirm the delayed reaction to the PPD.

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Response by:

Catherine A Curley, MD, MS Catherine A Curley, MD, MS
Assistant Professor of Medicine
School of Medicine
Case Western Reserve University