TB Skin Test (Mantoux)

The TB skin test is a way to find out if a person has TB infection. 

For this test, a small amount of testing material is placed just below the top layers of skin, usually on the arm.

Two to three days later a health care worker checks the arm to see if a bump has developed.

When a bump is felt the health care worker measures the size of the bump.

If the bump is of a certain size (varying with group) the test is significant and the person is presumed to have TB infection.

Once the doctor knows that a person has TB infection he or she will want to determine if the person has TB disease.

This is done by using several other tests including a chest X-ray and a test of a person's mucus (the material that is sometimes coughed up from the lungs).

Question: Should you get a skin test each year to check on TB?

Answer: Only if you are at high risk for getting or transmitting TB.

The advice for most people is to get a tuberculin test if you have symptoms or if you are living in close contact or have otherwise been in close contact with someone who recently came down with TB disease. (Some people get skin tests because of their jobs, in a school or hospital, for example, to make sure they have not contracted TB and will not infect others if they have TB.)

However, if you fall into one or more of the high-risk categories for TB noted earlier, for example, if you are HIV positive, or if you've never had a skin test before, or if there is no record of the last result, you should be tested.

If you're not sure, ask your doctor. TB can be prevented, even if you are at risk.