Tuberculosis Skin Test
(PPD Skin Test)

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Tuberculosis skin test facts

  • The tuberculosis skin test is also known as the tuberculin test or PPD test.
  • The PPD test is used to determine if someone has developed an immune response to the bacterium that causes tuberculosis (TB).
  • The standard recommended tuberculin test is the Mantoux test, which is administered by injecting a 0.1 mL volume containing 5 TU (tuberculin units) PPD into the top layers of skin of the forearm.
  • Skin tests should be read 48-72 hours after the injection.
  • The basis of the reading of the skin test is the presence or absence and the amount of induration (localized swelling).
  • A negative test does not always mean that a person is free of tuberculosis.
  • A person who received a BCG vaccine (administered in some countries but not the U.S.) against tuberculosis may also have a positive skin reaction to the TB test.
Medically Reviewed by a Doctor on 1/30/2014

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Tuberculosis Skin Test - Symptoms Question: What were the symptoms and signs of your tuberculosis infection?

Tuberculosis Diagnosis

Because TB may occur as either a latent or active form, the definitive diagnosis of active TB depends on the culture of mycobacteria from sputum or tissue biopsy. However, it may take weeks for these slow-growing bacteria to grow on specialized media.