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A normal person infected with the bacteria that causes tuberculosis Mycobacterium tuberculosis may not have any symptoms, is called latent TB infection and is not contagious. However, the bacteria can still progress to pulmonary tuberculosis. At that time, the IFN-gamma test was used to diagnose and detect tuberculosis early.
1. What is the IFN gamma test?
Interferon Gamma Release Tests (IGRAs) abbreviated as IFN gamma test, is performed to measure the release of Interferon Gamma (IFN-γ) by T lymphocytes from leukocytes, after mixing with specific antigens signal extracted from Mycobacterium tuberculosis (abbreviated as M. tuberculosis).
The IFN gamma test measures and evaluates the body's immune response to tuberculosis bacteria has the following advantages and disadvantages:
Advantages: Fast results (within 24 hours) and if vaccination is available - Asking for BCG also does not affect the results, does not give false positive results. Disadvantage: Need to conduct specimen testing within 8 hours after sampling. In subjects including young children (< 5 years old), people exposed to tuberculosis, immunocompromised, re-testing is not enough information to conduct testing. There are 2 types of IFN gamma test available:
QuantiFERON®-TB Gold In-Tube test (abbreviated as QFT-GIT): Measures the concentration of Interferon Gamma released. T-SPOT®.TB test (abbreviated as T-Spot): Measures T lymphocytes on white blood cells that are activated and release Interferon Gamma.
2. Significance of IFN gamma . test
The IFN-gamma test is significant in the diagnosis and detection of latent tuberculosis. However, it should be noted that a negative test result may mean that TB bacteria are not present, and a positive result may mean that TB bacteria are present.
To evaluate the patient's latent or active TB infection, additional tests should be performed such as:
PCR of TB bacteria; MGIT tuberculosis culture; X-ray or CT scan of the lungs; Clinical examination symptoms: Frequent cough with sputum, or low-grade fever in the afternoon, rapid unexplained weight loss. When there is a positive IFN gamma test result, the patient should soon be advised to conduct more tests to diagnose tuberculosis (latent or active), and be closely monitored to reduce the risk. community infection.
Nên kết hợp IGRAs với các xét nghiệm khác để góp phần chẩn đoán chính xác bệnh lao tiềm ẩn
3. In which groups is the IFN gamma test indicated?
IFN gamma test is indicated for the following groups of people to detect latent TB:
People in close contact with TB patients: Health workers, caregivers; Young children (>5 years) in close contact with a TB patient (active); People living with people with acquired immunodeficiency such as HIV disease ; Using drugs that suppress the immune system; Have diabetes that is not controlled; Have been vaccinated against tuberculosis BCG; Difficulty in examining and testing TB skin disease.
4. What to tell your doctor before performing an IFN gamma test
IFN gamma test is indicated when the patient has signs of risk, suspected latent TB infection. Therefore, before conducting the test, it is necessary to inform the doctor of the following information to avoid affecting the test results:
Having HIV immunosuppressive disease, kidney disease, lymphoma; Are you taking medications that affect the immune system, such as steroids, cyclosporin, or cancer medications? Have a viral infection that causes measles, influenza, respiratory infections, fever; Vaccinated within 1 month; History of tuberculosis or exposure to a TB patient, vaccination against BCG tuberculosis, or travel to or living in an endemic area.
5. IFN gamma . test results
Each type of gamma IFN test can give the following results:
QFT-GIT test: Results can be positive, negative, or undetermined. T-Spot test: Results can be positive, negative, suspect, or inconclusive. To avoid affecting test results, IFN-gamma testing should be performed on the day of vaccination with live vaccine or 4-6 weeks after vaccination. Particularly for the case of vaccination against chickenpox, at least 1 month after vaccination can IFN gamma test.
If you suspect that you have tuberculosis, you need to go to a reputable hospital to conduct an examination and conduct an IFN-gamma test as soon as there are signs of the disease. Currently, Vinmec International General Hospital is one of the leading prestigious hospitals in the country, trusted by a large number of patients for medical examination and treatment. Not only the physical system, modern equipment: 6 ultrasound rooms, 4 DR X-ray rooms (1 full-axis machine, 1 light machine, 1 general machine and 1 mammography machine) , 2 DR portable X-ray machines, 2 multi-row CT scanner rooms (1 128 rows and 1 16 arrays), 2 Magnetic resonance imaging rooms (1 3 Tesla and 1 1.5 Tesla), 1 room for 2 levels of interventional angiography and 1 room to measure bone mineral density.... Vinmec is also the place to gather a team of experienced doctors and nurses who will greatly assist in diagnosis and detection. early signs of abnormality in the patient's body. In particular, with a space designed according to 5-star hotel standards, Vinmec ensures to bring the patient the most comfort, friendliness and peace of mind.
Please dial HOTLINE for more information or register for an appointment HERE. Download MyVinmec app to make appointments faster and to manage your bookings easily.
