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2 Step Tb Skin Test

When Should I Call My Doctor About Tb

PPD Test 2 Step PPD Testing || Statcare

If you have symptoms of TB , such as a persistent cough, chest pain and fever, or think youve been exposed to someone with an active TB infection, its important to see your provider as soon as possible.

TB can be deadly if its not properly treated. Most cases of TB can be cured if you take antibiotics as directed by your healthcare provider. Both active and latent TB should be treated, but the type and medications and how long you need them are different if you have active vs. latent TB.

A note from Cleveland Clinic

TB testing and screening are essential for public health. Since TB can be deadly and spreads from person to person easily, its important to get tested if you have symptoms, are at high risk for developing active TB or are at high risk of being exposed to the infection. Once you know your results, your healthcare provider will let you know if you need to undergo further tests. Dont be afraid to ask your provider questions. Theyre here to help you.

What Is A Two

Best practice indicates that a two-step tuberculin skin test involves two tests performed within one to four weeks of each other. The second test can be completed up to one year from the first test, provided there has not been an exposure to infectious tuberculosis disease during that time period. It cannot be done less than one week from the first test.

How A Tb Skin Test Works

A TB skin test measures your immune systems response to a purified protein derivative solution injected under your skin. PPD is a protein that comes from the bacteria that causes TB Mycobacterium tuberculosis.

Its not live bacteria, and it wont make you sick. If youve ever been exposed to the TB bacteria, your skin will react to the antigens by developing a firm, red bump at the site of the injection within three days.

How a TB blood test works

In most cases, if youve been infected with TB, blood cells from your blood sample will release a protein called interferon-gamma when mixed with antigens derived from Mycobacterium tuberculosis in a laboratory.

To conduct the tests, laboratory scientists mix your blood sample with antigens and controls and measure the reaction using a method called immunoassay. Theyll interpret your results as negative, positive or indeterminate.

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How Does A Tb Test Work

Both types of TB tests the skin test and blood test work by measuring your immune systems response to antigens taken from the bacterium that causes TB: Mycobacterium tuberculosis. An antigen is any substance that causes your immune system to produce antibodies against it. This means your immune system doesnt recognize the substance and is trying to fight it off.

What Does A Positive Tb Test Look Like


A positive TB skin test will look like a firm, red bump. Your provider will measure the size of the firmness of the bump . Your provider considers your particular risk factors to determine the results of your test. Youre considered positive if your bump is:

  • Greater than or equal to 5 millimeters and you have a compromised immune system.
  • Equal to 10 mm and youre a healthcare worker.
  • Equal to 15 mm and you dont have any risk factors.

Even if you think you know the result of your test based on your skins appearance after 48 to 72 hours of when you were first injected with the liquid, its important to see your healthcare provider for the second visit to get a proper assessment. Theyre specially trained to observe your skin for a reaction and need to document your result.

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When Should I Know The Results Of My Tb Test

It takes 48 to 72 hours to complete a skin TB test. Once you have your second visit with your healthcare provider, theyll be able to tell you if your skins reaction indicates that you may or may not have a TB infection.

In most cases, you should get the results of your TB blood test within one to two days, though it could take longer.

What Does A Positive Skin Test Mean

A positive skin test does not mean that you are sick with tuberculosis. In most cases, all it means is that you may have been exposed to the tuberculosis germ at some time during your life.

If you have a positive skin test, you will need a medical examination and chest x-ray to be sure you are not sick with tuberculosis. Your doctor may want to put you on some medication to prevent inactive TB from turning into active TB.

If you have had a positive test, it is important that you not get any further TB skin tests in your lifetime as they will continue to be positive. If you are asked to get another TB skin test for school, work or volunteering, see your doctor to get a chest x-ray done instead.

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What Should I Expect During A Tb Test

The TB testing process is different based on what kind you get the skin test or the blood test.

TB skin test process

A TB skin test requires two or three visits with a healthcare provider. During the first visit, they inject fluid into your arm. On the second visit, the healthcare provider assesses your skins reaction to the injection. If still negative, the third visit is needed.

During the first visit:

  • A healthcare provider will clean and disinfect the skin on your lower inner arm.
  • Theyll inject a small amount of fluid with a tiny needle under the skin on your lower inner arm.
  • The provider may mark the injection site by circling the area with a pen. This makes it easier for them to find the area when assessing the reaction.
  • A small bump will form where they injected the fluid. It should go away in a few hours.

Youll then return to your provider within 48 to 72 hours so that they can look for a reaction on your arm where they injected the fluid. Firm swelling and redness at the site may indicate a TB infection. Its important to go to your second appointment to get an official result. If you dont return within 72 hours, youll need to take the test again. Immunocompromised individuals and those with frail skin conditions may not have reliable skin test results.

TB blood test process

You can expect to experience the following during a blood test, or blood draw:

The entire procedure usually takes less than five minutes.

Who Performs A Tb Test

Tuberculin Skin Test

Any healthcare provider who is specially trained in performing and assessing the results of a TB skin test can perform the test.

A healthcare provider called a phlebotomist usually performs blood draws, including those for a TB blood test, but any healthcare provider who is trained in drawing blood can perform this task. They then send the sample to a lab where a medical technologist prepares the samples and performs the test.

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Should I Get A Tuberculosis Skin Test If I Am Pregnant

You may be tested under your healthcare practitioner’s supervision if there is a need to do so. Since TB can be passed from mother to child during pregnancy, if you are at an increased risk of contracting TB, your healthcare practitioner may want you to have a TST or IGRA done. Either of these is considered safe during pregnancy.

Tuberculosis Screening Testing And Treatment Of Us Health Care Personnel: Recommendations From The National Tuberculosis Controllers Association And Cdc 2019

Weekly / May 17, 2019 / 68 439â443

Lynn E. Sosa, MD1,2 Gibril J. Njie, MPH3 Mark N. Lobato, MD2 Sapna Bamrah Morris, MD3 William Buchta, MD4,5 Megan L. Casey, MPH6 Neela D. Goswami, MD3 MaryAnn Gruden, MSN7 Bobbi Jo Hurst7 Amera R. Khan, MPH3 David T. Kuhar, MD8 David M. Lewinsohn, MD, PhD9 Trini A. Mathew, MD10 Gerald H. Mazurek, MD3 Randall Reves, MD2,11 Lisa Paulos, MPH2,12 Wendy Thanassi, MD2,13 Lorna Will, MA2 Robert Belknap, MD2,11

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When Should A Two

A two-step TST should be performed if subsequent TSTs will be conducted in the future . The two-step protocol needs to be performed once only if properly performed and documented. It never needs to be repeated. Any subsequent TST can be one step, regardless of how long it has been since the last TST.

If the first test in the two-step TST is positive, the second TST is not required. The individual should be medically evaluated with a chest x-ray and symptom review.

Active And Inactive Tuberculosis

Testing Health Care Workers

Inactive or latent TB occurs when a person becomes infected but the body’s immune system is able to prevent the bacteria from making you sick.

Active TB disease occurs when the body’s immune system is unable to stop the growth and spread of the bacteria resulting in illness.

Both inactive and active TB are treatable and curable.

TB treatment is free and is accessible through Region of Waterloo Public Health.

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Normal And Critical Findings

PPD Skin test Interpretation Based on CDC Guidelines

The result of the PPD test is positive or negative. However, the size of the induration diameter cutoff for the test to be positive is based on certain risk factors.

As the diameter cutoff increases, the sensitivity of this test declines, and the specificity increases. For instance, the sensitivity of this test for 5 mm diameter cutoff positivity is the highest, whereas, 15 mm diameter cutoff positivity is more specific.

Induration of 5 mm and more is considered positive in:

  • Immunosuppressed individuals
  • HIV infected individuals.

An induration of 10 mm or more is considered positive in:

  • Immigrants from endemic/high prevalence countries in the last 5 years.
  • High-risk area employees and residents. For example, prisons, nursing homes, and homeless shelters.
  • Injection drug abusers.
  • Children less than four years of age.
  • Chronic medical conditions that increase the risk of tuberculosis include diabetes, kidney failure, malignancy, etc.
  • Infants/Children/adolescents exposed to high-risk categories.

An induration of 15 mm or more is considered positive in:

  • Always considered positive in any person. Healthy individuals without any risk factors for TB.
  • Patients who do not meet any of the above criteria

Positive PPD Skin test

If the infection risk is very high, the PPD test need not be repeated. The positive PPD test is usually followed by TB symptom assessment, physical exam, and chest radiograph.

Negative PPD Skin test

Tb Skin Test At Public Health

TB skin tests are publicly funded for the following individuals:

  • Immigrants and refugees from endemic countries
  • International students from endemic countries
  • Canadian-born travellers who have travelled to endemic countries for more than one month
  • Clients with medical risk factors who have a referral from a health care provider
  • Contacts of active TB cases

Due to the COVID-19 pandemic, Public Health is not providing TB skin testing clinics.

NOTE: We do not administer TB skin tests that are required for employment or volunteer purposes or admission to a program or study in a school, college, university or other educational institution.

Please check with your family doctor to see if they provide TB skin testing. If you do not have a family doctor, or your doctor does not provide TB skin testing please refer to the list below.

TB Skin Test Providers in Waterloo Region


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How Does A 2 Step Tb Test Work

In a typical test, a doctor injects a small amount of purified protein derivative into a patient. After a few days, the doctor will measure the size of the reaction your skin has to the injection in order to diagnose you. If youve had TB in the past, its likely that your skin wont react at all, sometimes resulting in a false negative.

A 2 Step PPD Test is very accurate. The second skin test enhances the accuracy of this test. Getting a 2 Step PPD Test is the easiest, most accurate way to understand whether or not you have tuberculosis.

The 2-Step PPD Test requires an extra appointment, which can be a concern for some people as many medical offices are not open on weekends and holidays. The test may need to be redone if you dont get into the doctor to have it read in the 48-72 hour time frame. Statcare however makes it easy for you to make appointments on your terms. We are open every day of the week including holidays for extended hours. Our staff can accommodate your 2 Step PPD Test anytime and at any location so you can get your results as soon as possible.

The Difference Between Ppd Testing And 2 Step Ppd Testing

Mantoux Test (aka. PPD or TST)

The main difference between PPD Testing and a 2 Step PPD Test is the accuracy of the test results. A negative 2 Step PPD Test is a more reliable screen if youve not been around anyone with TB. All healthcare workers and people employed in daycare centers and prisons should have this test. Without it, there is a risk that you wont know if you contract TB. And without the proper treatment, the infection can spread to other places in your body, like your brain and your spine. Avoid that danger by requesting a 2 Step PPD Test from your doctor.

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What Type Of Results Do You Get From A Tb Test

The results of a TB skin test or blood test will be either negative or positive. Its important to remember that these tests only show if youve been exposed to the TB infection not if your infection is active or latent. Those who have received TB vaccine may show false-positive skin test results.

Positive TB test

If your TB skin test or blood test is positive, it likely means youve been exposed to the bacterium that causes TB. Your healthcare provider will likely order more tests to help make a diagnosis. Tests that diagnose active TB infections include chest X-rays and laboratory tests on a sputum sample. Sputum is the thick mucus that you cough up from your lungs. Its different than spit or saliva. Youll need to be treated for TB, whether its latent or active.

Negative TB test

If your TB skin or blood test is negative, you likely havent been exposed to the TB bacterium. A negative TB skin test means your skin didnt react to the liquid. You may need further testing if your results were negative, but you have symptoms of TB.

Who Should Be Screened For Tb

You may need a TB test if you have symptoms of an active TB infection or if youre at higher risk for getting TB. In addition, some childcare centers, hospitals and other facilities require you to be tested for TB in order to work there.

Symptoms of an active TB infection include:

  • Bad cough lasting longer than two weeks.

You may be at higher risk for getting TB if you:

  • Are a healthcare worker who interacts with and cares for people.
  • Live or work in a place with a high rate of TB infection, including homeless shelters, nursing homes and prisons.
  • Have been exposed to someone who has an active TB infection.
  • Have a medical condition or take medication that weakens your immune system.
  • Use intravenous drugs.
  • Have traveled or lived in an area where TB is endemic, including countries/regions other than USA, Canada, Australia, New Zealand, Japan, Northern and Western Europe.

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Understanding Your Test Results

If you have a positive test result and you have symptoms or are considered at high risk of TB exposure, youll likely be prescribed medications to clear up the infection and relieve symptoms.

If youre low risk and have a positive test, your doctor may recommend a TB blood test to confirm the diagnosis. The TB skin test is less accurate than the blood test, so you could have a positive skin test and a negative blood test.

What Is A Tb Test

generic two step tb test form

A TB test checks to see if you have been infected with Mycobacterium tuberculosis complex, which is the bacteria that causes tuberculosis . There are two types of latent tuberculosis infection screen tests: a skin test and a blood test.

A TB skin test is also called a Mantoux test or tuberculin skin test . A TB blood test is also called an Interferon-Gamma Release Assay , but you might sometimes hear QuantiFERON . TB skin tests are more common and are the preferred type for children under age 5. But blood tests for TB are becoming more common, especially for healthcare workers and those who have compromised immune systems.

TB skin and blood tests can show if youve ever been infected with M. tuberculosis complex, but they cant distinguish between a latent or active TB infection. Youll need additional tests to see if you have an active infection.

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Do I Need A 2 Step Ppd Test

Thankfully, advances in treatment and testing have greatly reduced the number of people who contract tuberculosis in the United States. However, as recently as 2014, the World Health Organization estimated that 1 in 4 people with TB go undiagnosed. That means, to keep yourself healthy, you should routinely get tested for TB. You definitely need a 2 Step PPD Test if youve had TB in the past and suspect that youve been exposed to TB again. But even if youve never had tuberculosis, you can request a 2 Step PPD Test. This will help you avoid a false negative read.

See your doctor immediately if youve been around someone with TB or you start exhibiting symptoms. Some common signs include fever, unexplained weight loss, coughing, and night sweats.

Statcare is open every day, including holidays, for extended hours. If you are wondering, Is there a 2 step TB test near me?, come to one of our five convenient locations to start your test. Our trained staff will be able to walk you through the test, accurately read the results, and help you through any necessary treatment plan.

If youre curious about any other services we offer, we have a convenient list for you. We even offer online doctor visits for those times when you just cant get out of bed. Take a look or come visit us anytime.


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