Question: How Do I Read My TB Blood Test Results?

Can TB be detected through blood test?

The tuberculosis (TB) blood test, also called an Interferon Gamma Release Assay or IGRA, is a way to find out if you have TB germs in your body.

The TB blood test can be done instead of a TB skin test (Mantoux).

There are two kinds of TB blood tests: QuantiFERON®-TB..

What happens if your TB test is positive?

A positive reaction usually means that you have been infected by someone with TB disease . If you have recently been infected with TB bacteria, your TB skin test reaction may not be positive yet .

Can you have TB and not know it?

A person with latent, or inactive, TB will have no symptoms. You may still have a TB infection, but the bacteria in your body is not yet causing harm. Symptoms of active TB include: A cough that lasts more than three weeks.

How did I get latent tuberculosis?

Latent TB occurs when a person has the TB bacteria within their body, but the bacteria are present in very small numbers. They are kept under control by the body’s immune system and do not cause any symptoms.

How do you read a TB report?

The skin test reaction should be read between 48 and 72 hours after administration. A patient who does not return within 72 hours will need to be rescheduled for another skin test. The reaction should be measured in millimeters of the induration (palpable, raised, hardened area or swelling).

What does a negative TB test look like?

The test is “negative” if there is no bump (or only a very small bump) at the spot where the fluid was injected. A negative TB skin test usually means that you don’t have TB. In some situations, you may need to have another TB skin test later.

How do you know if your TB test is positive or negative?

TB Skin Testing Results If you have a raised, hard bump or there’s swelling on your arm, you have a positive test. That means TB germs are in your body. But it doesn’t always mean you have active tuberculosis disease. If you don’t have a reaction, your test is negative.

Is a TB test positive if its red?

The test may be seen as positive if the skin where you were injected is hard, raised, red, and swollen. But redness alone is not considered a positive test result. In many cases, a healthy immune system will surround the TB bacteria soon after you are infected.

What can cause a false positive TB test?

False positive results happen with the skin test because the person has been infected with a different type of bacteria, rather than the one that causes TB. It can also happen because the person has been vaccinated with the BCG vaccine. This vaccine is widely used in countries with high rates of TB infection.

How do you know if your TB skin test is positive?

A skin test is the only way to tell if you have TB infection. The test is “positive” if a bump about the size of a pencil eraser or bigger appears on your arm. This bump means you probably have TB infection. Other tests can show if you have TB disease.

What organ does TB attack most?

TB most commonly affects the lungs – what’s known as the body’s pulmonary system.

Can a TB test look positive after a few hours?

Doctors should read skin tests 48-72 hours after the injection. The basis of the reading of the skin test is the presence or absence and the amount of induration (localized swelling). A negative test does not always mean that a person is free of tuberculosis.

What is the most accurate test for tuberculosis?

The most commonly used diagnostic tool for tuberculosis is a simple skin test, though blood tests are becoming more commonplace. A small amount of a substance called PPD tuberculin is injected just below the skin of your inside forearm.

How long does TB blood results take?

How long does it take to get the results back? This varies and depends on how frequently the laboratory in your area carries out the test. Unlike the TST, individuals do not need to return 2–3 days later in order to have the test read. Results can be available in 24 hours.

How accurate is TB blood test?

Though IGRAs are not 100% accurate—no lab test is—and can sometimes give results that are not clearly positive or negative (indeterminate), the IGRA blood test is an improvement over the skin test in detecting TB. Another advantage of the IGRA is that it requires only one healthcare visit to have a blood sample drawn.

Can a person with TB go to work?

If you have TB disease of the lungs or throat, you are probably infectious. You need to stay home from work or school so that you don’t spread TB bacteria to other people. After taking your medicine for a few weeks, you will feel better and you may no longer be infectious to others.

Does TB blood test require fasting?

The QuantiFERON TB Gold Blood Test is an in vitro assay to aid in the diagnosis of both latent and active infection with Mycobacterium Tuberculosis. Preparation: No fasting required. This test requires a special collection kit that may not be available at all LabCorp locations.

What is the gold standard for TB diagnosis?

The diagnostic gold standard for active tuberculosis (TB) is the detection of Mycobacterium tuberculosis (MTB) by culture or molecular methods. However, despite its limited sensitivity, sputum smear microscopy is still the mainstay of TB diagnosis in resource-limited settings.