How is tuberculosis (TB) diagnosed?

Children who are at risk for contracting TB should receive a TB test. There are two TB tests for TB infection: a skin test or a blood test.

  • During a tuberculin skin test, a small needle is used to place tuberculin (testing material) under the skin on the forearm. In two to three days, the patient returns to the healthcare provider, who will check the reaction to the test. If there has been an infection, the patient’s skin will swell and redden at the injection site.
  • A TB blood test measures how a person’s immune system reacts to the bacteria that cause TB.

To test for TB disease, other tests such as a chest X-ray and a sample of sputum (mucus that is coughed up from the lower airways) may be needed. Diagnosis of tuberculosis in children is difficult, because children are less likely to have symptoms of tuberculosis. Also, sputum samples are difficult to collect from children.

Last reviewed by a Cleveland Clinic medical professional on 11/10/2018.

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