What Happens After a Positive Tuberculosis Skin Test Results?

M. DePietro

Positive tuberculosis skin test results do not necessarily indicate a person has active tuberculosis or is contagious. Usually, after a person comes back with a positive purified protein derivative (PPD) skin test, additional testing is needed to determine if active tuberculosis is present. Additional tests will include a chest X-ray and a review of his or her symptoms. Depending on those results, further tests and treatment may be needed.

Chest x-rays are used to help diagnose tuberculosis.
Chest x-rays are used to help diagnose tuberculosis.

To understand what happens after positive tuberculosis (TB) skin test result, its important to know what a TB test is. During a PPD test, also known as a mantoux test, a small amount of tuberculosis antigens — called tuberculin — is injected under the skin. The spot of the injection is examined between 48 and 72 hours after the injection to check for a raised area of the skin, known as an induration. If a TB skin test is positive, it means the person has a response to the bacteria that causes tuberculosis. This does not necessary mean the person has symptoms or active disease.

A person with active tuberculosis will be treated with a course of oral antibiotics.
A person with active tuberculosis will be treated with a course of oral antibiotics.

If positive tuberculosis skin test results occur, the first test ordered is usually a chest X-ray. An X-ray can determine if infiltrates or lesions are present in the lungs, which may indicate active TB. A symptom checklist will also usually be reviewed to determine if signs of TB, such as weight loss, coughing up blood, fever, and night sweats are present. If the chest X-ray is normal and no symptoms are present, no further testing is usually needed.

Further diagnosis is required after a positive tuberculosis skin test.
Further diagnosis is required after a positive tuberculosis skin test.

In some cases, people without active TB, but who have positive test results, may be put on medication. The bacteria that causes TB can show up in someone with a positive skin test, but may be dormant. Medication may be given as a precaution to prevent the bacteria from becoming active in the future.

Tuberculosis is a contagious disease that may cause the lymph nodes to swell.
Tuberculosis is a contagious disease that may cause the lymph nodes to swell.

When a chest X-ray indicates signs of TB or symptoms are present, a person may have active tuberculosis. At this point, sputum samples will need to be analyzed to confirm the presence of the bacteria. The person will also need to be kept away from close contact with other people to prevent spreading the disease. If active TB is present, antibiotic medication will be given to treat it.

Once a person has a positive tuberculosis skin test, he will likely have positive tests in the future. PPD skin tests are a routine requirement for some types of employment and school admission. For people with a history of a positive PPD skin test, a yearly symptom checklist is usually performed instead.

Individuals with tuberculosis are not eligible to donate blood.
Individuals with tuberculosis are not eligible to donate blood.

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Discussion Comments

ysmina

@anamur-- There is another TB test which can tell you for sure if you have TB or not. You need to see an infectious diseases specialist to receive it.

I was sent to one after I started developing side effects to TB medications. I tested negative with this other TB test and was taken off the medications immediately.

To be honest with you, I have mixed emotions about this whole process and the tuberculin skin test. A lot of people seem to test positive for it. I do know that many people are able to take the medications without problems and prevent developing active TB in the future. But it does seem like the skin test is not very thorough and the TB blood test would be a better option.

serenesurface
@ddljohn-- I'm going through the same process now. I also tested positive in the skin test, my chest X-ray came back clear and my doctor wants to put me on medication.

I'm not sure if I should go ahead with the medication treatment though. I'm Southeast Asian and from what I've heard, almost all Southeast Asians test positive for TB when they get the mantoux skin test. It's supposed to have something to do with the vaccinations that are given to newborns in Asia.

I've read about the potential side effects of the TB medication and it's quite serious. It can cause liver damage and I think most people have to take it for nine months. I'm not sure that all of this is necessary.

Isn't there another route I can take to find out what my probability of developing active TB is?

ddljohn

I had a TB positive skin test result last month. I was extremely worried when my doctor first told me because I thought it meant that I had tuberculosis. But my doctor explained that the positive result just means that I have been exposed to the bacteria in the past, but I might not have tuberculosis.

I had an x-ray done the same day which showed no signs of tuberculosis. My doctor prescribed me a medication that I'm currently taking. I have to take it for another five months. The medication will kill any TB bacteria that might be dormant in my body.

My doctor also mentioned that I will always give positive result to a TB skin test. That's why in the future, I only need to get an x-ray done if I develop any symptoms of tuberculosis.

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