What is a Tuberculosis Skin Test?
Tuberculosis is an infectious disease that can wreak havoc on your lungs and then spread to other parts of your body. A Mantoux tuberculin skin test, or a TB test, refers to a standardized method of determining if someone has Mycobacterium tuberculosis, the bacteria that causes tuberculosis. Here's what you need to know about the testing process.
What Happens During a TB Test?
For the skin test, 0.1 mL of the TB antigen, or tuberculin purified protein derivative, will be injected under the top layer of the skin on the inner side of your forearm. A small bump, or wheal, will form under the skin from the fluid that is injected. The medical professional who is administering the test may mark the area by drawing a circle around the wheal with a pen. You will be advised to leave the area exposed and to return to your physician in two to three days to have the test area examined. You may experience some itching at the injection site, but you should refrain from manipulating the area or placing a bandage over it as doing so can interfere with the reading of the skin test.
Deciphering Your Test Results
During your return visit, your physician will assess the test area to determine your reaction to the TB antigen. Typically, if there is just redness at the test site, this means that you have not been infected with the bacteria.
However, the presence of a firm red bump at the injection site indicates positive results and that you have been infected with the tuberculosis bacteria at some point in the past. The size of the bump and what type of risk group you may belong to are factors that are used to determine if you have the disease. The bump will be interpreted as a sign of infection if:
- You have a small, firm bump and are part of a high-risk group.
- You have a larger, firm bump and are part of a low-risk group.
Positive results do not imply that you have an active infection of Mycobacterium tuberculosis. To determine whether the TB is latent or active, it will be necessary to undergo additional tests, such as a chest x-ray.
Why Should You Get a TB Test
Tuberculin skin tests are recommended if you:
- Have been in proximity to another person who has tuberculosis.
- Have recently undergone an organ transplant.
- Exhibit the symptoms of TB, including night sweats, inexplicable weight loss, persistent coughs or constant fatigue.
- Have had a chest x-ray that produced abnormal results.
- Have a weakened immune system.
- Are a healthcare worker who is likely to be exposed to tuberculosis.
At PrimeCare Urgent Care, you can find out whether or not you have TB by taking our $25 TB test. If you are ill and are exhibiting symptoms of tuberculosis or any other serious condition, stop by our clinic to receive the professional health care you need.