TB Testing
TB testing helps determine whether a person has been infected with the bacteria that cause tuberculosis (TB). Depending on the reason for testing and a person’s medical history, testing may involve a TB blood test or TB skin test, with additional evaluation when needed.
Surprise Care provides TB testing as part of its primary care services for patients in Surprise, AZ. Whether testing is needed for employment, school, travel, a potential exposure, or another health-related requirement, understanding which test is appropriate and what the results mean can help patients take the next step.
Understanding Tuberculosis and TB Infection
Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis. Although TB most commonly affects the lungs, it can affect other parts of the body.
A person can have TB infection without having active TB disease. People with inactive or latent TB infection generally do not have symptoms and cannot spread TB bacteria to others. Active TB disease occurs when the bacteria become active and cause illness, and pulmonary or laryngeal TB can spread to other people.
This distinction is important because a TB test indicates whether TB infection may be present, but a positive result does not by itself establish that someone has active TB disease. Additional medical evaluation may be necessary. The Centers for Disease Control and Prevention (CDC) recommends further evaluation after a positive TB test.
Who May Need TB Testing?
Routine TB testing is not necessary for everyone. The CDC recommends targeted testing for people who have an increased risk of TB infection or who have a specific reason for screening.
TB testing may be appropriate for people who:
- Have been exposed to someone with infectious TB
- Have symptoms that could be associated with TB
- Have certain risk factors for TB infection
- Need screening for employment or school
- Need testing for immigration or other official requirements
- Are advised to receive testing by a healthcare provider or public health authority
Some people with TB infection do not experience symptoms, which means testing can be appropriate even when someone feels healthy.
TB Testing for Employment, School, and Other Requirements
Certain workplaces, schools, healthcare settings, and other organizations may require documentation of TB screening. Requirements can differ depending on the organization, position, and applicable regulations.
Patients should determine what their employer or institution requires before scheduling a test. The required documentation may specify the type of test, timeframe, or other criteria that must be met.
For this reason, it is helpful to bring any instructions or forms provided by the organization when attending a TB testing appointment.
The Two Main Types of TB Tests
There are two primary methods used to test for TB infection: TB blood tests and TB skin tests.
A TB blood test, also known as an interferon-gamma release assay (IGRA), uses a blood sample to measure the immune system’s response to TB proteins. According to the CDC, two FDA-approved TB blood tests are currently available in the United States: QuantiFERON-TB Gold Plus and T-SPOT.TB.
A TB skin test, commonly called the Mantoux tuberculin skin test, involves injecting a small amount of testing material into the skin. The injection site must then be examined by a trained healthcare professional within the appropriate timeframe.
The choice between a blood test and skin test depends on factors such as the reason for testing, vaccination history, medical circumstances, and whether the patient can return for a follow-up reading.
Choosing the Appropriate TB Test
TB blood tests can be useful for people who may have difficulty returning for a skin-test reading. The CDC also generally prefers TB blood tests for people who have received the BCG vaccine because BCG can affect the interpretation of a TB skin test.
A healthcare provider can review the patient’s circumstances before determining which testing method is appropriate. Patients should also provide information about previous TB testing, possible exposure, travel, vaccination history, and any relevant symptoms.
What to Expect During TB Testing
The testing process depends on the method being used.
For a TB blood test, a healthcare professional collects a blood sample that is analyzed by a laboratory. The patient generally does not need to return specifically to have the blood test interpreted.
A TB skin test involves an injection into the skin, followed by a required follow-up visit for the injection site to be examined. Returning within the specified timeframe is important because the result is based on how the site responds.
Before testing, patients should let their healthcare provider know about previous TB tests, known exposure to TB, symptoms, previous BCG vaccination, and any history of TB treatment.
Understanding Positive and Negative TB Results
A negative TB test generally means TB infection is unlikely, but it does not always rule out infection. Additional evaluation may be necessary when someone has recently been exposed to TB, has symptoms, or has certain medical conditions that affect the immune response.
A positive test generally indicates TB infection. It does not, by itself, determine whether a person has inactive TB infection or active TB disease.
Further evaluation may include a medical examination, chest X-ray, or other laboratory testing depending on the patient’s symptoms and circumstances.
Patients should follow up with a healthcare provider after a positive result so the result can be properly evaluated.
When to Seek Medical Evaluation for Possible TB
Testing may be appropriate when a person has been exposed to TB or needs screening for a specific reason. Medical evaluation is also important when symptoms suggest active TB disease.
Symptoms can include a persistent cough, chest pain, coughing up blood or sputum, fever, night sweats, unexplained weight loss, or fatigue. These symptoms can have many possible causes, so experiencing them does not automatically mean a person has TB.
Anyone with concerning symptoms or a known exposure should discuss the situation with a healthcare provider rather than relying on a screening test alone.
Schedule TB Testing in Surprise, AZ
TB testing can help identify possible TB infection when screening is appropriate for a person’s circumstances. Understanding the available testing methods and following the correct steps for result interpretation can help patients address work, school, travel, exposure, and other testing needs appropriately.
Patients seeking TB testing in Surprise, AZ can contact Surprise Care at (623) 244-8797 to discuss their testing needs and schedule an appointment.
Frequently Asked Questions (FAQs)
How long does a TB skin test take?
The initial TB skin test involves a small injection into the skin. A healthcare professional must then examine the injection site during the specified follow-up window to interpret the result.
Is a TB blood test different from a TB skin test?
Yes. A TB blood test requires a blood sample and measures the immune response to TB proteins. A TB skin test involves an injection into the skin followed by an examination of the injection site. The appropriate method depends on the patient’s circumstances.
Can I get a TB test if I do not have symptoms?
Yes. People may need TB testing because of employment, school, exposure, travel, or other risk factors even when they feel healthy. TB infection can occur without symptoms.
What does a positive TB test mean?
A positive result generally indicates TB infection, but it does not determine whether the infection is inactive or active. Additional medical evaluation may be needed to determine the appropriate diagnosis and next steps.
Do I need TB testing for work or school?
Some employers and educational institutions require TB screening. Requirements vary, so patients should check with the organization requesting the test to determine what type of testing and documentation they need.
Should I bring anything to my TB testing appointment?
If testing is being requested by an employer, school, or other organization, bring any forms or instructions they provided. Information about previous TB testing, vaccination, exposure, or treatment can also help the healthcare provider evaluate the current test appropriately.