CDC Logo Tuberculosis Information CD-ROM   Image of people
jump over main navigation bar to content area
TB Guidelines
Surveillance Reports
Slide Sets
TB-Related MMWRs and Reports
Education/Training Materials
Ordering Information


U.S. Department of Health and Human Services


Education Materials > Publications > Self-Study Modules on TB > Module 3 > Diagnosis of TB > The Tuberculin Skin Test

Self-Study Modules on Tuberculosis

This is an archived document. The links are no longer being updated.

Module 3: Diagnosis of Tuberculosis Infection and Disease

The Tuberculin Skin Test

Patients with symptoms of TB disease are often given a tuberculin skin test to detect exposure to and infection with TB. However, as many as 20% of patients found to have TB disease have a negative tuberculin skin test reaction. For this reason, patients with symptoms of TB disease should always be evaluated for TB disease, regardless of their skin test results.

Furthermore, for patients with symptoms of TB disease, clinicians should not wait for tuberculin skin test results (48 to 72 hours) before starting other diagnostic tests.

A tuberculin skin test is not necessary for patients known to have had a previous positive tuberculin skin test reaction.

Study Questions 3.21-3.24

3.21. What are the four steps in diagnosing TB disease?

3.22. What parts of a patient's medical history should lead a clinician to suspect TB?

3.23. What are the common symptoms of pulmonary TB disease? What are the general symptoms of TB disease (pulmonary or extrapulmonary)?

3.24. For patients with symptoms of TB disease, should clinicians wait for tuberculin skin test results before starting other diagnostic tests?



Released October 2008
Centers for Disease Control and Prevention
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention
Division of Tuberculosis Elimination -

Please send comments/suggestions/requests to:, or to
CDC/Division of Tuberculosis Elimination
Communications, Education, and Behavioral Studies Branch
1600 Clifton Rd., NE - Mailstop E-10, Atlanta, GA 30333