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TB skin test done. Noticed redness on skin with no bumps. Do I have TB?

Mar 2013
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i had a tb test done 2 days ago. Its red but there is no bump. Does it mean i have tb
Posted Sun, 21 Apr 2013 in Cancer
Answered by Dr. Aarti Abraham 21 minutes later
Thanks for your query.

The TB skin test (also called the Mantoux tuberculin skin test) is performed by injecting a small amount of fluid (called tuberculin) into the skin in the lower part of the arm. A person given the tuberculin skin test must return within 48 to 72 hours to have a trained health care worker look for a reaction on the arm. The health care worker will look for a raised, hard area or swelling, and if present, measure its size using a ruler. Redness by itself is not considered part of the reaction.

The skin test result depends on the size of the raised, hard area or swelling. It also depends on the person’s risk of being infected with TB bacteria and the progression to TB disease if infected.

Positive skin test: This means the person’s body was infected with TB bacteria. Additional tests are needed to determine if the person has latent TB infection or TB disease. A health care worker will then provide treatment as needed.
Negative skin test: This means the person’s body did not react to the test, and that latent TB infection or TB disease is not likely.

An induration of 5 or more millimeters is considered positive in

-HIV-infected persons

-A recent contact of a person with TB disease

-Persons with fibrotic changes on chest radiograph consistent with prior TB

-Patients with organ transplants

-Persons who are immunosuppressed for other reasons (e.g., taking the equivalent of >15 mg/day of prednisone for 1 month or longer, taking TNF-a antagonists)

An induration of 10 or more millimeters is considered positive in

-Recent immigrants (< 5 years) from high-prevalence countries

-Injection drug users

-Residents and employees of high-risk congregate settings

-Mycobacteriology laboratory personnel

-Persons with clinical conditions that place them at high risk

-Children < 4 years of age

- Infants, children, and adolescents exposed to adults in high-risk categories

An induration of 15 or more millimeters is considered positive in any person, including persons with no known risk factors for TB. However, targeted skin testing programs should only be conducted among high-risk .

Merely redness should not worry you. Please return to your healthcare provider to have the induration measured and have correct interpretation of the test.

A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria. It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease. Other tests, such as a chest x-ray and a sample of sputum, are needed to see whether the person has TB disease.

I hope this helped you.
Take care, and feel free to ask further questions.
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