Many are interested in how a blood test for tuberculosis is taken and done. This procedure is quite common. This is a modern answer to the old types of disease diagnosis. But what are blood tests? What features do they include? And how should a citizen, based on the results, understand whether he has a disease or not? Understanding all this is not as difficult as it seems. You do not need to have a medical education in order to draw a conclusion based on the results. So what knowledge should a citizen have regarding TB testing?
About the disease
To begin with, let's analyze what kind of disease we are talking about? The thing is that tuberculosis is a serious chronic disease, extremely dangerous and contagious. It is transmitted by airborne droplets or through household appliances. It is very common in the world, but in the initial stages of tuberculosis is quite difficult to detect.
This disease can affect all human organs. Therefore, it is impossible to accurately predict what the outcome will be. In order to recognize the disease in time, a complex of studies is required. For example, do a blood test fortuberculosis.
The most common type of disease is the one that affects the lungs. It is with him that many develop an association. Quite often, the manifestation of the disease can be confused with the common cold. Tuberculosis itself is not serious in any way. Especially in the early stages of development.
Types of disease diagnosis
Many are interested in the name of a blood test for tuberculosis. Knowing this is important. Indeed, with timely treatment, the disease recedes, and the person does not face serious negative consequences of the disease. It is important to know that there are several types of diagnostics in the world at the moment.
Which ones exactly? The following can be distinguished:
- Mantoux reaction;
- sputum analysis;
- bronchoscopy;
- IFA;
- QuantiFERON-TB Gold;
- IGRA;
- PCR.
In some cases, a complete blood count is done. This is usually done in the initial stages to identify the likelihood of a disease. And confirmation occurs only through the methods indicated earlier. Now they have come up with another method that replaces a blood test for tuberculosis - diaskintest. It does not come into contact with blood, but at the same time it helps to detect tubercle bacillus in the human body. It has a number of its advantages and disadvantages. It was introduced in Russia in 2016.
ELISA
Now a little about blood tests. After all, they are considered the most informative. Most often, this term means an ELISA study. Such an analysisblood for tuberculosis allows you to detect the presence of antibodies to tuberculosis bacilli.
In principle, not the worst option. All the patient has to do is take a blood test. Usually they take a venous one, it provides a more accurate result. Unfortunately, ELISA is now considered to be not very informative. Indeed, according to this study, it will not be possible to say at what stage the disease is, if any. But such a procedure helps, as already mentioned, to identify the presence of antibodies to the disease in the body.
Fortunately, medicine does not stand still and there are other ways to detect the disease. And related to blood. What are the pros and cons they have? How are they carried out? How can you understand that a person is sick?
PCR diagnostics
Much more informative and effective is the PCR blood test for tuberculosis. This is a modern method that allows you to determine the presence of a tubercle bacillus. It is extremely informative if not blood is taken for research, but sputum.
As a rule, PCR diagnostics is prescribed for suspicious symptoms that are somewhat reminiscent of tuberculosis. However, as doctors say, this study does not give a 100% result in the case of blood. It is possible only when the patient is sick with tuberculous sepsis. Otherwise, PCR-diagnosis of blood is not very effective.
Mantu
What else should I pay attention to? A blood test for tuberculosis in children, as a rule, is not performed. Most often they are assignedthe so-called Mantoux reaction. This technology makes it possible to detect the presence of the disease with high, but not 100% accuracy.
How is the analysis done? A special preparation is administered to the child by subcutaneous method. Next, a few days you need to observe the injection site. If there is no tuberculosis, then this area will remain unchanged. You may notice only slight swelling and discoloration of the skin - it will become more pink.
In the presence of tuberculosis, the injection site swells, swells, the tumor begins to grow. Sometimes it can take on a bluish color. In this situation, the child is re-assigned to Mantoux. Or a blood test for tuberculosis (ELISA or PCR) is done, which confirms or refutes the result of the test.
Mantoux is sometimes wrong
However, you should pay attention to the fact that the Mantoux reaction is far from the best way to diagnose tuberculosis in the body. The point is that this analysis is often wrong.
How else can you interpret the analysis? Deciphering a positive Mantoux reaction is simple. It can be observed at:
- exacerbation of common chronic diseases;
- asthma;
- allergies;
- infectious diseases;
- compromised immunity;
- epilepsy.
Accordingly, even a positive test result does not give accurate indications of the presence of the disease. Therefore, a blood test for tuberculosis instead of Mantoux is more effective and informative. It is necessary to exclude all the previously listed development optionsevents. Only then will it be possible to judge the presence of the disease.
CBC
If Mantoux is positive, don't panic. It has already been said that this method of diagnosis is not the best. You need to take a blood test. With pulmonary tuberculosis (and not only), some changes occur in the body. Which ones?
The thing is that in the initial stages, the blood remains unchanged. Therefore, a general or clinical analysis does not make sense. Depending on the "neglect" of the disease, certain indicators will change. A general blood test for tuberculosis sometimes really helps to make sure the presence or absence of the disease.
Nevertheless, you should not rely on him alone. After all, blood and its composition change, depending on many factors. Therefore, either ELISA diagnostics or PCR is recommended. But we should not forget about the general blood test either.
Transcript according to general analysis
What indicators should I pay attention to if there is a possibility of tuberculosis infection? With the active stage of the disease, a general blood test will really help to understand that the pathogen is in the blood.
How exactly? The fundamental is the ESR. Normally, in a person, this indicator will depend on age. You should rely on the following data:
- children under 10 - up to 10 mm/h;
- women under 50 - up to 20 mm/h;
- women over 50 - up to 30mm/h;
- men under 50 - 15 mm/h maximum;
- after 50 - up to 20 mm/h.
However, ESR in pregnant and sick people may increase. In tuberculosis, as a rule, this indicator increases to approximately 50 units or more. Therefore, you should pay attention to it. If the erythrocyte sedimentation rate in the blood significantly exceeds the norm, we can conclude that there is a high probability of infection.
Features of a blood test
What features should be taken into account if it is decided to conduct an additional study for the presence of the disease under study? A blood test for tuberculosis instead of Mantoux is prescribed quite often. But at the same time, ELISA and PCR are often not enough for a final diagnosis. A complete blood count also does not fully show the picture of what is happening in the body.
You should pay attention to the fact that the doctor, if he suspects the presence of a tubercle bacillus in the body, prescribes a biochemical blood test. You can also do a separate study for the presence of protein. This will verify the results.
If there is tuberculosis, but only in an inactive form, then the protein indicator will be within the normal range. The acute form of the disease increases cholesterol, urea and lysozyme. In this case, albumin will be reduced.
A disease that affects the liver, increases indicators such as AST, ALT and bilirubin. All this is revealed by a blood test, while the Mantoux reaction does not provide such information. This fact must be taken into account.
Diaskintest
Now it is clear that if there are anyfears about the presence of the studied disease in the body, you can take a blood test for tuberculosis. Biochemistry and a general study are also additionally assigned. All this helps to comprehensively assess the situation and draw a conclusion about the presence of a disease in the body.
Nevertheless, now many people are talking about a new type of tuberculosis diagnosis, which allows the reagent not to come into contact with blood. We are talking about the previously mentioned diaskintest. This is a replacement for Mantoux. Is this study worth believing? What are its pros and cons?
This diagnostic method allows you not to contact with blood - this has already been emphasized more than once. So, with a weakened body, there is no chance of contracting the disease. For the patient, diaskintest resembles Mantoux. The study is required to be carried out annually. Usually every 12 months for people aged 8 to 17.
True, many point out that this type of body test for the presence of tuberculosis is not accurate. All this is due to the fact that, as with the Mantoux reaction, some factors can give a false positive result. And the person will be assigned either a second study or a blood test for tuberculosis.
Conclusion
Now it is clear how you can detect the presence of the disease under study using certain tests. QuantiFERON-TB Gold and IGRA are rare blood tests. They are screenings that indicate the content of antibodies and the presence of the disease. Almost never used in Russia.
You cannotice that even general and biochemical blood tests will help to identify tuberculosis in a particular case. It is enough to pay attention to some indicators. They will be broken. ESR in tuberculosis is necessarily increased. In general, only a doctor can make an accurate conclusion based on several studies. To confirm the diagnosis, you can take not blood, but sputum for analysis.
