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TB - How to read a skin test?



How to read a TB test? My bump is about 5mm, but also has some very fine bumps like a rash on it. Should I be concerned?


TB skin tests need to be read (in millimeters of induration measured across the forearm) at 48 to 72 hours after placement. Please have a nurse or a physician look at the TB skin test site on your arm, because experience in reading TB skin tests can help determine whether the bumps you see were due to the TB skin test or not. If there is any question whether or not it is positive, you can have the TB skin test replaced at a different site and read 48 to 72 hours later.

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Go to the Tuberculosis health topic, where you can:

Response by:

Lisa A Haglund, MD Lisa A Haglund, MD
Associate Professor of Clinical Medicine
College of Medicine
University of Cincinnati