Tuberculosis - QuantiFERON Test

Order a TB blood test to identify a tuberculosis infection with the QuantiFERON-TB Gold Plus test from Ulta Lab Tests. Learn about your health today!  

The QuantiFERON tb gold plus is a simple and very effective blood test that aids in detecting Mycobacterium tuberculosis, the bacteria that causes tuberculosis. Order yours today from Ulta Lab Tests and get your results confidentially online.    


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Tuberculosis is a communicable disease caused by infection with M. tuberculosis complex. Infection results in either acute disease or Latent TB Infection (LTBI), a non-communicable asymptomatic condition. The main purpose of diagnosing the latent stage is to consider medical treatment for preventing overt disease. Until recently, the tuberculin skin test was the only available method for diagnosing LTBI.

QuantiFERON®-TB gold eliminates false positive skin test due to BCG vaccination and most Non-Tuberculous Mycobacteria (NTM) and is an objective, reproducible qualitative test. There are no side effects or adverse reactions due to patient hypersensitivity, and no "booster effect", whereby the first test induces a false positive response on re-testing. There is no need for follow-up patient visits to obtain test results.

The TB blood test has several advantages over a skin test.  Blood testing requires only one visit to the lab while skin testing requires multiple visits to a doctor's office.  Blood testing for Tuberculosis is typically more accurate than a skin test.  Skin testing has a higher likelihood of false positive results, especially if a person has been previously vaccinated for TB. 

 


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Elevated RF is found in collagen vascular diseases such as SLE, rheumatoid arthritis, scleroderma, Sjögren's Syndrome, and in other conditions such as leprosy, tuberculosis, syphilis, malignancy, thyroid disease and in a significant percentage of otherwise normal elderly patients.

Rheumatoid factor is commonly used as a blood test for the diagnosis of rheumatoid arthritis. However, rheumatoid factor can also be present in individuals with other conditions such as lupus, infectious hepatitis, syphilis, mononucleosis, tuberculosis, liver disease, and sarcoidosis. Rheumatoid factor is an antibody that is detectable in the blood of 80% of adults with rheumatoid arthritis. Rheumatoid can be detected in the blood of normal individuals and of those with other autoimmune diseases that are not rheumatoid arthritis. In people with rheumatoid arthritis, high levels of rheumatoid factor can indicate a tendency toward more aggressive disease and/or a tendency to develop rheumatoid nodules and rheumatoid lung disease. Rheumatoid factor is actually an antibody that can bind to other antibodies. Antibodies are normal proteins in our blood that are important parts of our immune system. Rheumatoid factor is an antibody that is not usually present in the normal individual. Rheumatoid factor is commonly used as a blood test for the diagnosis of rheumatoid arthritis. Rheumatoid factor is present in about 80% of adults (but a much lower proportion of children) with rheumatoid arthritis.

Rheumatoid Factor (IgA, IgG, IgM) 

Reference Range(s)

  • Rhematoid Factor (IgA)
    • ≤6 Negative
    • >6 Positive
  • Rhematoid Factor (IgG)
    • ≤6 Negative
    • >6 Positive
  • Rhematoid Factor (IgM)
    • ≤6 Negative
    • >6 Positive

Rheumatoid factor is commonly used as a blood test for the diagnosis of rheumatoid arthritis. However, rheumatoid factor can also be present in individuals with other conditions such as lupus, infectious hepatitis, syphilis, mononucleosis, tuberculosis, liver disease, and sarcoidosis. Rheumatoid factor is an antibody that is detectable in the blood of 80% of adults with rheumatoid arthritis. Rheumatoid can be detected in the blood of normal individuals and of those with other autoimmune diseases that are not rheumatoid arthritis. In people with rheumatoid arthritis, high levels of rheumatoid factor can indicate a tendency toward more aggressive disease and/or a tendency to develop rheumatoid nodules and rheumatoid lung disease. Rheumatoid factor is actually an antibody that can bind to other antibodies. Antibodies are normal proteins in our blood that are important parts of our immune system. Rheumatoid factor is an antibody that is not usually present in the normal individual. Rheumatoid factor is commonly used as a blood test for the diagnosis of rheumatoid arthritis. Rheumatoid factor is present in about 80% of adults (but a much lower proportion of children) with rheumatoid arthritis.

Tuberculosis (TB) Test - The QuantiFERON-TB Blood Test is used to aid in the diagnosis of both latent and active infections with the bacteria that causes Tuberculosis (TB). This test has been updated to offer the Quantiferon Gold Plus which has the same high level of specificity as the previous generation of testing along with an increased sensitivity of 94%.  This test is one of only 2 blood tests for TB approved by the FDA.  Tuberculosis is a bacterial disease that typically affects the lungs.  TB Bacteria is spread through the air from one person to another. While TB is not as common in the United States as it once was, there is the still a risk posed by TB infection.  It is estimated that 11 million people in the US have a latent Tuberculosis infection (LTBI).

 

Tuberculosis is a communicable disease caused by infection with M. tuberculosis complex. Infection results in either acute disease or Latent TB Infection (LTBI), a non-communicable asymptomatic condition. The main purpose of diagnosing the latent stage is to consider medical treatment for preventing overt disease. Until recently, the tuberculin skin test was the only available method for diagnosing LTBI.

QuantiFERON®-TB gold eliminates false positive skin test due to BCG vaccination and most Non-Tuberculous Mycobacteria (NTM) and is an objective, reproducible qualitative test. There are no side effects or adverse reactions due to patient hypersensitivity, and no "booster effect", whereby the first test induces a false positive response on re-testing. There is no need for follow-up patient visits to obtain test results.

The TB blood test has several advantages over a skin test.  Blood testing requires only one visit to the lab while skin testing requires multiple visits to a doctor's office.  Blood testing for Tuberculosis is typically more accurate than a skin test.  Skin testing has a higher likelihood of false positive results, especially if a person has been previously vaccinated for TB. 

 



Tuberculosis (TB) is a bacterial infection that is caused by Mycobacterium Tuberculosis and is a highly infectious disease. The bacteria primarily target the lungs but can affect other areas of the body, such as the central nervous system, urinary tract, bones, joints, and other bodily organs. A blood test called the Interferon Gamma Release Assay (IGRA) measures the immune response to antigens that are derived from the bacteria in order to screen for TB.

TB may either result in an active, progressive disease or inactive (latent) infection. In about 90% of people who have been infected, the immune system can control the spread of the disease and restrict it to just a few cells in the body. While the bacteria in these cells are inactive, they are still alive. This is referred to as an inactive or latent TB infection, and the person will present with none of the symptoms of TB and cannot transmit the disease.

However, should the immune system become compromised or weakened for any reason, the bacteria may become active, causing the mycobacterium to start growing again. This will result in TB that becomes symptomatic of the illness and is infectious, which means that it can be transmitted to others via respiratory secretions such as moisture, aerosols, and sputum that are expelled from the body when coughing, sneezing, breathing, talking, laughing or singing.

Although the IGRA blood test can accurately detect Tuberculosis, it is unable to differentiate between latent or inactive TB and active infections. Additional testing may be required to make this distinction, such as the AFB test for TB infections.

The QuantiFERON® (QFT-Plus) TB Gold Plus, formally known as the IGRA TB Test or Interferon Gamma Release Assay.

This test is not commonly used to screen general population groups but rather to test individuals who present with high-risk factors for TB, including:

  • Diseases that compromise the immune system like HIV and AIDS, which places them at a higher risk of contracting an active TB infection.
  • Cramped living conditions like prisons, schools, migration camps, homeless shelters, etc. that increase exposure and vulnerability to the disease.
  • People working in healthcare or other occupations that may expose them to carriers of active TB.
  • Any person who has come into close contact with a person/s who have a confirmed case of active TB.
  • People who have traveled to live in or spent extended periods in foreign countries or areas where TB is prevalent.
  • People who inject illegal substances or drugs.

The IGRA test has become the preferred means if diagnosing TB, but the Tuberculin Skin Test (TST) may still be performed to screen for TB.

The IGRA test uses a blood sample to measure the amount of gamma interferon that is released by blood cells when they are exposed to TB antigens. Select laboratories only perform the test as viable white blood cells are required for accurate testing, which must be tested within a specified time frame.

The CDC (Centers for Disease Control and Prevention) in conjunction with the American Thoracic Society and the Infectious Diseases Society has compiled a list of recommendations for preferred IGRA testing if:

  • A person is not likely to return for their TST to be evaluated.
  • A person is five years of age or younger.
  • Has a high probability of being infected with latent TB.
  • Has little to no risk of becoming immuno-compromised, resulting in the development of an active TB infection.
  • There is evidence that warrants a Latent Tuberculosis Infection Test.
  • If the person has received the BCG (Bacille Calmette-Guérin) vaccine, which could interfere with the TST interpretation and results. BCG is not commonly administered in the U.S.A. unless for the treatment of some forms of cancer. It is, however, used in countries that do have a high prevalence of TB.
  • If the IGRA test is unavailable or when the TST test is determined to be a more suitable option due to cost or other extenuating circumstances.

Under the following circumstances, these agencies do NOT recommend testing for Tuberculosis in those who are unlikely to be infected, people who are at low risk of contracting the disease, or where the disease is not progressing.

If latent TB testing is a requirement for any reason, such as for employment or legal reasons, the following is suggested:

  • IGRA testing for those who are five years and older.
  • A second test (either IGRA or TST) to confirm a positive result from the first test. Only if both tests are positive can the person be positively diagnosed with TB.

In addition, IGRA testing can be ordered:

  • Annually for persons at high risk either because they have the disease and are prone to a weakened immune system or because they live and/or workaround others that are at high risk.
  • Before a person joins a group or population that is at high risk like healthcare workers.
  • When a person has been exposed to a person with an active infection. This test should only be administered a few weeks after exposure. It can take about six weeks from the time of exposure and initial infection before a positive result can be detected in the blood.
  • A person who has lived for an extended period in a country where TB is prevalent.
  • A person who presents signs and symptoms of tuberculosis, including chronic cough producing sputum or phlegm that may contain bloody streaks, fever, chills, night sweats, and inexplicable weight loss.

Understanding the TB Test Results

If the IGRA test result is positive, it means that the person has been exposed to TB and that they may have either an active TB infection or a latent TB infection. If there is any suspicion that the infection may be active, the healthcare practitioner must take a full medical history, provide a thorough medical examination and perform any other relevant tests such as a chest x-ray, AFB laboratory testing, and any other tests to confirm the diagnosis.

If the IGRA test result is negative, it is unlikely that the person has been infected with Tuberculosis. However, there is still a possibility that a TB infection may be present. The test may have been performed too early after exposure or infection to detect the infection. A person should only be tested about six weeks after possible exposure or infection in order to get a positive reaction from the IGRA test. If there is still a suspicion that a person may have contracted TB even though the IGRA result was negative, the healthcare practitioner should perform a second IGRA test later or confirm with the alternative TST test.

The IGRA test may provide a false-positive result in rare cases, especially due to exposure to the Mycobacterium species Mycobacterium Kansasii. If there is a concern of a false-positive result, chest x-rays and other tests must be performed to rule out a TB infection. If active TB is suspected, smears, cultures and sensitivity testing as part of the AFB test should be used to confirm a diagnosis as well as the susceptibility to drugs of the strain of Mycobacterium causing the infection.

Pregnant women who are at high risk may be required to be screened for Tuberculosis as the disease is transmittable from mother to child during pregnancy. Both TST and IGRA are safe for TB testing during pregnancy.