Alternate Names: Purified protein derivative

How Performed: The test site (an area with hair, usually the forearm) is cleansed. The PPD (taken from dead TB bacteria) is then injected into the area. You may need to keep the area dry for 48 to 72 hours. You will need to go back to the health care provider after 48 and 72 hours for the results to be seen. The duration of the reaction is important.

How To Prepare: There is no special preparation. The health care provider should know if you have had a positive skin test for tuberculosis; if you have ever had TB; if you have recently been vaccinated for measles, mumps, rubella, polio, or other diseases; or if you are taking any medication, especially steroids (cortisone) or immunosuppressive drugs.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:

• infant test or procedure preparation (birth to 1 year)
• toddler test or procedure preparation (1 to 3 years)
• preschooler test or procedure preparation (3 to 6 years)
• schoolage test or procedure preparation (6 to 12 years)
• adolescent test or procedure preparation (12 to 18 years)

How It Feels: There will be a brief sting as a needle is inserted just below the skin surface.

Risks: There is a slight risk of anaphylactic shock (a severe reaction).

Why Performed: The test is performed to evaluate exposure to the TB bacteria.

Normal Values: A negative reaction or no inflammation at the test site is normal.

Abnormal Results: The significance of the reaction depends on the circumstances and the size of the reaction on the skin. The reaction is measured in millimeters of induration (hard swelling) at the site. For example, if you have relatives who have tuberculosis, a small reaction could be important. How long the reaction lasts is as important as the size.

Cost:

Special Considerations: The body does not recognize the difference between a previous TB infection and a current infection. Other tests may be necessary.