What is an important reading time frame for the tuberculin skin test?

The important reading time frame for the tuberculin skin test is 48-72 hours after administration. This interval is crucial because it allows enough time for the immune response to develop, which is indicated by the formation of swelling or induration at the injection site. If the test is read too soon, at 24 hours for instance, the reaction may not be fully formed and could lead to a false negative result. Waiting beyond 72 hours, especially up to a week, can also be problematic as the reaction may start to resolve, again potentially leading to inaccuracies in interpreting the results. Therefore, the designated 48-72 hour window is essential for accurately determining the presence of tuberculosis exposure.