Methods for diagnosing a variety of diseases, such as tuberculosis, do not stand still. One of the newest methods is the quantiferon test - this reaction is able to diagnose the presence of infection in a test tube, without the introduction of tuberculin samples under the skin. Gradually, he is gaining increasing popularity in comparison with the classical Mantoux and Diaskintest trials, but the diagnosis has its own characteristics, among which there are negative ones.
What is the quantiferon test of
Until now, the most common methods of diagnosing tuberculosis were Mantoux, Diaskintest and other methods of skin introduction of biological material. Tubinferonovy test - a modern method that allows you to take on the study of blood from the vein, while avoiding adverse reactions. The test reveals the presence of a Koch bacillus in people who had previously received BCG vaccine due to good diagnostic specificity. No special patient preparation is required for the study.
Indications for the
procedure One of the main advantages of the method is its safety. Gamma-interferon test for tuberculosis is carried out in vitro, without the introduction of active substances under the skin. This replacement Mantou has proved to be a highly specific test, capable of detecting even a small amount of sensitizing substances. One of the important advantages is the absence of contraindications, which distinguishes favorably from the Mantoux and Diaskintest trials. The study is assigned to the following groups of individuals:
- to people with intolerance to active agents of tuberculin;
- for patients with exacerbation of inflammatory processes;
- with psoriasis, seasonal skin allergy;
- for children in quarantine.
How is the
performed? The quantifyferon test method works as follows: the patient is withdrawn blood from the vein, and then under laboratory conditions, the test binds to the interferon gamma antigens. This substance is formed in cells infected with mycobacteria tuberculosis. The result is compared with NIL-control tubes. The test identifies tuberculosis even at an early stage of infection and does not give an erroneous reaction if previously vaccinated against the disease.
analysis results As with any ELISA( enzyme-linked immunoassay) assay, the quantiferon assay can produce three possible outcomes: positive, negative, and doubtful. Positive means a reaction to the presence in the body of pathogens of tuberculosis. Additional medical advice is required. Positive analysis does not mean an open form of the disease, sometimes diagnosing a latent one.
In the test, the result is compared with the sample in the NIL( control) test tube, the test tube with antigen( Ag) and mitogen( Mitogen). In a healthy human gamma interferon is not found in the body, Mitogen is a control-positive capacity, and the Antigen tube contains the antigens of tuberculous mycobacteria. Patient's blood sample is compared by analytical method. Sometimes the result is dubious, which means the need to repeat the study in a month. The diagnosis is made only by the doctor taking into account the patient's anamnesis.
Advantages and disadvantages of
The tubinferon test is considered one of the most modern methods. What distinguishes it from skin tests: it can be done unlimited number of times, it does not cause allergic reactions and is safe for the patient. Studies confirm high specificity, that is, the technique is able to "distinguish" antibodies formed after vaccination against infection with tuberculous mycobacteria. Interpretation of results is quantified, which means increased objectivity. However, there are drawbacks.
- 10-11% - false-negative results due to specificity of sensitivity.
- The cost of research is higher than that of analogues.
- Laboratories doing this test, while there are only in large cities.
- The method does not distinguish the latent carriage of the Koch's rod from the open form of tuberculosis, therefore the treatment should not be based solely on the results of the study, specialist consultation is necessary.
Where to make a quantiferon test for tuberculosis
The prevalence of the method of research is still low in our country. The easiest way is to make an interferon test for tuberculosis in Moscow, St. Petersburg. Gradually this service appears in laboratories of other major cities of the Russian Federation, such as Krasnodar, Samara, Kazan, Yekaterinburg, Novosibirsk. If you are interested in the technique, first of all, you should contact the Scientific Research Institute of Tuberculosis at the Russian Academy of Medical Sciences or the Institute of Phthisiopulmonology at the Moscow State Medical University. Sechenov.
Price for the quantiferon test
In any laboratory, the study is chargeable. The price for this type of research in Moscow and St. Petersburg ranges from 1800 to 3500 thousand rubles. Remember that the interpretation of this test and the conclusion based on its results should be carried out only by professionals, therefore, before conducting a study, consult a specialist.