Serological laboratory analysis of what. Why do a serological blood test

When is a serological blood test used?

Serology is a science that allows you to qualitatively study the properties of human blood serum. This is one of the most important branches of immunology, which pays special attention to the interaction of antigens and antibodies.

There are two main types of serological reaction according to the mode of action:

1. Straight. Also called two-component. This type includes agglutination reactions, as well as passive hemagglutination.
2. Indirect, or three-component. Inhibition of hemagglutination or neutralization reaction occurs.

At the moment, this type of research is actively used for the following purposes:

1. Determination of a person's blood group.
2. Identification of the number of antibodies that have arisen as a result of the appearance of an infectious agent in the human body. In this case, it is necessary to conduct a comprehensive assessment of the chemical reaction that appeared due to the addition of a special disease antigen to the serum.
3. Determination of an infectious disease by antigens, while antibodies must be added to the blood for effective expression of the antigen.

If there are any problems during the clotting process, then appropriate measures should be taken urgently. Otherwise, inaction can lead to heart attacks, thrombosis or stroke.

The main indications for performing a serological blood test

To date, this technique is actively used to determine the following diseases:

• amoebiasis;
• giardiasis;
• opisthorchiasis;
• syphilis;
• toxocariasis;
• toxoplasmosis;
• trichinosis;
• cysticercosis;
• echinococcosis.

In addition, such studies are used in the following cases:

• examination of a pregnant woman;
• detection of diseases of the cardiovascular system;
• examinations that are necessary in venereology and urology;
• liver studies;
• various examinations before or after operations;
• determination of pathologies in the process of blood clotting;
• phlebeurysm;
• autoimmune diseases;
• identification of effective treatment;
• after the completion of appropriate therapy.

Thus, with the help of a serological blood test, a person can be identified in a timely manner. different kinds the most difficult diseases. This allows you to prescribe an effective treatment plan.

Serological blood test: pros and cons

Each type of survey has its own advantages and disadvantages that should be considered.

The advantages of the methodology include the following aspects:

• reliability of the result;
• affordable cost;
• the result is ready in a fairly short time - just a day is needed for complete readiness;
• the method allows to control the quality and effectiveness of the entire treatment.

The main disadvantage is that certain diseases can not be detected immediately, since there is an incubation period.

How to prepare for the analysis

This analysis is given exclusively on an empty stomach. To avoid various errors and get the most reliable result, it is recommended to adhere to the following rules:

1. For a few days, it is better to exclude too fatty and spicy foods from your diet.
2. Try to be less nervous and anxious.
3. Minimize the consumption of foods high in sugar.
4. Limit exercise.
5. Avoid alcohol and nicotine.

Thanks to the above rules, you can get the most reliable result.

Decryption

Immunoblot method

Non-treponemal reactions are evaluated in the laboratory. If the result is negative, a dash is displayed in the column. If flakes of sufficiently large sizes were found, then the indicator will be from +3 to +4. If medium-sized flakes were detected, the result will be +1 and +2.

It is important to remember that infection is detected only after one to two months.

Treponemal tests are more accurate. But the designations are largely the same.

Remember that tests are individual, and only a professional laboratory technician can truly accurately decipher them. You should not engage in self-treatment, as health can only be trusted by specialized doctors.

Serological blood test - what is it? Unfamiliar procedures always scare and make you suspect the worst. But serology is just a study active ingredients blood serum, and it is not at all necessary to suspect illness when receiving a referral for this analysis. Blood serology is done not only when diseases are suspected, but also for a preventive purpose: for example, when applying for a job, everyone must be tested for markers of hepatitis and HIV.

What is this study

A serological blood test is one of the simplest and most affordable methods for identifying the type of pathogen and the degree of the body's immune response.

A serological test is carried out in order to identify infectious diseases that a person has or confirm their absence. The analysis is based on the interaction of antibodies or antigens contained in the serum with the added reagent. The agglutination reaction resulting from the interaction allows you to determine the type of pathogen and at what stage the infectious process is.

Blood tests are carried out in 2 ways:

1. The antigen that caused the infectious disease is added to the serum. Antibodies in the blood to the pathogen immediately enter into a chemical reaction. In this way, you can determine how strong the body's immune response is, as well as the severity of the infectious process.
2. The second method determines the type of pathogenic agent. With it, human antibodies developed against a specific pathogen are added to the serum. If the pathogen is in the human blood, then agglutination will occur.

The group and Rh of human blood are almost also determined when the components of the patient's biomaterial are mixed with sera of various groups.

A feature of these tests is that they allow you to quite accurately determine the type of pathogen and the degree of production of antibodies to it.

Therefore, do not be surprised when a doctor gives a referral for tests: antibodies developed against hepatitis C will not protect the body from other types of hepatitis. The same happens with other infections. The norm when deciphering the data is the zero content of antibodies or antigens.

What are the implications of the study data?

Having learned what a serological blood test is, many patients will want to know what its decoding will give.

With the help of the received data, you can:

• identify the pathological microorganism early stages infectious process;
• control the development of the disease and the degree of effectiveness of the treatment process;
• the ability to conduct samples frequently, due to the financial availability of the reagent;
• the result can be obtained within a few hours, which is very important for treatment in a hospital;
• the patient almost does not require special preparation before taking the biomaterial.

This examination is prescribed not only to detect infections: in the same way, oncological processes, allergic agents, disorders in the endocrine system and some other ailments are detected.

A slight disadvantage of this method can be considered that sometimes a false positive or false negative result is obtained. This can happen in pregnant women or if the patient has consumed certain foods or drinks the day before.

If a positive result is revealed during the initial interpretation of the data, then the examination is always prescribed again to exclude errors in the diagnosis.

How to prepare for donating blood

Despite the simplicity of the research and the fact that the result is almost not affected by external factors, nevertheless, in order to obtain the most reliable data, laboratory assistants recommend doing a little preparation on the eve of the delivery of the biomaterial:

• exclude fatty and spicy foods from the diet;
• eat less sweets and do not drink sugary carbonated drinks;
• stop drinking alcohol;
• limit physical effort (athletes are advised to skip training, and people engaged in heavy physical labor should take time off from work);
• avoid stressful situations.

All of the above factors can affect the transcript data, and the result may be a false positive.

But, as mentioned earlier, the first identified positive reaction, especially if there are no symptoms accompanying the identified ailment, this is not always an indicator of pathology.

Before prescribing a re-delivery of the material, the doctor always finds out what happened to the patient the day before the test, and gives recommendations on how to properly prepare for the examination.

Serological analysis is just an unfamiliar name, in fact, this study has been carried out more than once in most children and adults, because it can be used to identify the pathogen in a timely manner and monitor the effectiveness of the treatment process.

Serology is a branch of science that studies the processes that occur in human blood serum. It is an applied discipline that is at the intersection of immunology, biochemistry and laboratory diagnostics. Translated from Latin, "serum" means serum. What is "blood serum" and where does it come from? What can be determined by serological analysis?

Serum and serological reactions

Blood is a unique liquid tissue, which, in addition to the most important function - the transfer of oxygen to the tissues and the removal of carbon dioxide from them - also performs a lot of useful work. It transports various compounds, hormones are secreted into it, sent to the target organs from the endocrine glands with "special assignments".

Blood performs a protective function, due to the antibodies present in it, which are represented by class proteins. They protect us from the introduction of a purulent infection and predatory leukocytes - which are constantly looking for and destroying microbes. Normally, blood is mostly sterile (see article). How can all these and many other processes take place at the same time?

Very simple. Blood is heterogeneous in composition. If whole blood is placed in a test tube, and a little sodium citrate or heparin is added to it so that it does not clot, and then centrifuged, the contents of the test tube will separate into two layers. The first will contain cells, and above - a part of the liquid base that does not contain cells. This is plasma, or otherwise - serum.

Serum contains simple substances: chloride, sodium, potassium, magnesium ions. It has a pH of 7.36 - slightly alkaline. It contains proteins, fats, carbohydrates, bilirubin, urea, creatinine, enzymes, antibodies. Serum is the substrate for many biochemical, immunological and serological tests.

Everyone knows the "biochemistry" of blood. But one cannot speak of a biochemical study in the singular, a clarification is necessary. The doctor informs the patient that he is assigned to see protein fractions, sugar, and so on. Total method biochemical analysis about a hundred metabolites and compounds can be detected, but such a detailed and expensive analysis is hardly needed.

A serological study is also a whole group of similar reactions that occur in the serum when certain reagents are introduced into it. They are recorded in a quantitative (so much is allocated) or qualitative (is it allocated or not allocated) form. But, alas, this is too general a wording. There is too much in plasma.

What does serology do in terms of laboratory diagnostics, and how can it be useful to the patient?

Serology in practice

Serological analysis is “sharpened” only for the search for two things in plasma: antigens and antibodies. It is known that all pathogenic microorganisms and bacteria secrete special factors of pathogenicity, or harmfulness - antigens, toxins and other substances. In response, the body first learns to recognize a new source of danger, and then trained lymphocytes produce special proteins - gamma - globulins, or antibodies. Each antibody approaches the antigen molecule and blocks its active centers, approaching it like a "key" to a "lock". Here, the laboratory conducting serological analyzes is engaged in the detection of a wide variety of antigens and the antibodies formed on their introduction.

You can even say that serological analysis is a biochemical study that is aimed at finding infectious diseases.

Methods of serological diagnostics and its possibilities

Since serum is a liquid, and many serological reactions are associated with the introduction of drops, dilution of solutions, multiplicity - the basis of serology is titer. As a result of the analysis, you can read, for example, "antibody titer 1/10". The doctor says you are fine. But if in the analysis, for example, the titer is 1/500, then the doctor grabs his head and says that you are infected. What do these fractions mean? After all, the second fraction is much smaller than the first, but why is it more dangerous?

Very simply: it is the degree of dilution. In the first case, serum diluted 10 times (10%) reacted with a specific antigen, and in the second - diluted 500 times (0.2%). In the second case, we are talking about a very high concentration of antibodies in a sick person, which, even in such a dilution, are detected by a serological test. What tricks, besides the antibody titer, exist in the diagnosis?

These studies reflect the changes or dynamics of the body's antibodies and defenses. They are good at assessing the intensity of immunity that occurs after properly administered vaccinations (post-vaccination immunity). Serological diagnosis in a modern laboratory most often uses two methods: and the immunofluorescence reaction with labeled antibodies (RIF).

The tasks of a serological study are:

1. Determination of antibodies in serum to an infectious disease, using reactions with known antigens. That is, for example, a doctor prescribes an examination for a suspected infection, for example, on. A reaction with typhoid antigen is put to identify specific antibodies produced only against typhoid bacteria.
2. The second task can be considered the reverse. In the serum, an antigen, or waste products of microorganisms, is determined using well-known diagnosticums, which are called antisera.

The classic reactions include: the agglutination reaction and its expanded form, or passive hemagglutination. There is a precipitation reaction, a lysis reaction, a complement fixation reaction, and so on. It is hardly necessary to describe the features and technique of staging each of these reactions. Instead, it is better to conclude by listing the pros and cons of serological tests.

Advantages and disadvantages of the method

All serological methods have some advantages and disadvantages. A big plus is a fairly high level of reliability, but at the same time, cross-reactions cannot be ruled out. In the event that a person has any autoimmune pathology and a large number of various immune complexes circulate in the blood, then false positive reactions are also possible, so one cannot speak of one hundred percent certainty.

In the event that a person is sick or has recently had a similar disease, or has been vaccinated against an infection whose pathogen has related antigens, a false positive or cross-reaction may result.

A big plus is the fact that the serological blood test is performed quickly. Unlike bacteriological research When colonies of microorganisms need several days or even weeks to grow, serological blood tests are prepared within a day.

As a rule, these studies are inexpensive and quite accessible to all categories of the population.

Perhaps the most important drawback is the inability in some cases to distinguish when a person is sick and when he is healthy, but antibodies remain circulating in his blood after recovery. An example is, which is the cause of stomach ulcers. After its complete cure, the patient has antibodies for 2 years, and they will be detected when deciphering the results, both in the case of re-infection and if there is no infection. Therefore, the serological method of diagnosis must necessarily be supplemented by other methods.

If a person falls ill for the first time, then it is necessary to conduct research no earlier than 2-3 weeks after the onset of the disease, since antibodies may simply not be developed in an earlier period. Therefore, all serological research methods cannot be considered methods of rapid diagnosis, in the first days after the disease.

Finally, serological studies are targeted: reactions are carried out on suspected infections. You can’t just donate blood so that “serology shows some kind of” disease. And in this sense, the usual, routine seeding on nutrient media has a great advantage.

Serological reactions are based on the ability of antigens and antibodies to interact, forming immune protective complexes in the blood during a disease. A blood test, therefore, by the nature of the chemical serological reaction when either an antigen or an antibody is added, helps to determine the presence of an infection in the body.

What is a serological blood test?

A serological blood test is a method of laboratory blood testing, with the help of which infectious diseases are diagnosed and the stage of development of the infectious process is determined. The results are based on varying degrees of interaction between antigens and antibodies, which helps to identify the serological chemical reaction.

A serological blood test is used in such situations:

• determination of the amount of antibodies against infectious pathogens in the body; with such an analysis, the antigen of the pathogen is initially added to the blood serum, and then the chemical reaction that occurs is evaluated;
• the opposite situation is when the infection is determined by the contained antigens; then antibodies are added to the blood to detect the antigen;
• also this analysis is used in determining the patient's blood type.

If there are deviations in the process of blood clotting, especially if there is hypercoagulability, then this can lead to bad consequences, such as heart attack, stroke or thrombosis.

Preparing for a serological blood test to diagnose infections

A blood test for serological reactions is performed on an empty stomach. For research, blood serum is used. In it, during the study, the interaction of antibodies and antigens is determined.

Indications for a serological blood test for the diagnosis of infections

This method of laboratory research is used to determine infectious diseases, such as:

• lyamliosis;
• amoebiasis;
• toxoplasmosis;
• cysticercosis;
• opisthorchiasis;
• toxocariasis;
• trichinosis;
• echinococcosis.

Serological analysis is also prescribed in such situations:

• with liver disease;
• with autoimmune diseases;
• with varicose veins;
• with cardiovascular pathology;
• with deviations in blood clotting;
• when examining pregnant women;
• examination before and after surgery;
• to determine how effectively the treatment is being carried out;
• again after the end of the course of treatment.

Basically, this analysis is used in venereology and urology.

Serological blood test for the diagnosis of infections - the norm

The norm of the result of the analysis for serological reactions is the absence of antibodies to pathogens, which indicates the absence of infections in the body. However, as a rule, this does not happen, since there are already grounds for the appointment of this serological analysis.

It is always carried out twice to determine the dynamics of the disease, since a single determination of the interaction of antibodies or antigens does not reflect the picture of infection. An indicator of infection is the increase in the number of bonds between antibodies (immunoglobulins) and antigens at the next examination.

Serological blood test for the diagnosis of infections - elevated

An increased number of complexes of antibodies and antigens in the body indicates the presence of an infectious disease in the body. With an increase in indicators in the blood, specific chemical reactions are carried out that help determine the disease and its stage.

Serological blood test for the diagnosis of infections - reduced

The result cannot be reduced, since “zero” is an indicator of the norm.

What can influence the result?

When passing any analysis, the main thing is to follow the rules for preparing for it. And make sure that the blood sampling takes place in sanitary conditions, so that nothing foreign gets into the tested blood. And it is important to take the analysis on an empty stomach. On the previous day, do not overload the body with fatty foods, alcohol and sugary drinks. Eliminate stress and exercise.

Serological blood test- This is a laboratory test used to diagnose infectious diseases and determine the stage of the infectious process.

For analysis, blood serum obtained by removing fibrogen, a component responsible for blood clotting, is used for analysis. This technology gave the method its name: the term "serology" is derived from the Latin word serum (serum) and the Greek logos (teaching).

Serological analysis is based on the fact that any infection, any foreign agent, entering the body, causes a response from our defense system. on the defensive the immune system produces antibodies designed to destroy antigens - infectious agents and other foreign agents. Each antigen has its own antibodies; by their presence in the blood, one can conclude about the type of infection and its activity in the body.

In the process of research, serological reactions are used in two directions:

• to confirm the diagnosis, an antigen corresponding to the this disease, and the response indicates the presence (or absence) of antibodies.
• if it is necessary to determine the causative agent of the infection (antigen is not known), antibodies are added to the serum. The type of antibody that caused the reaction will indicate the genus and species of the microorganisms present.

When is a serological blood test ordered?

A serological blood test is prescribed for the following purposes:

• for the diagnosis of the disease, if the diagnosis requires confirmation of the presence of the causative agent of the disease;
• in order to prescribe a course of treatment, since different pathogens may respond differently to different drugs.

Serological analysis in the "Family Doctor"

Serological blood test - basic research in gynecology and urology. It is used to diagnose and sexually transmitted diseases, primarily HIV, syphilis (), herpes, cytomegalovirus, toxoplasmosis, and other diseases.

In other branches of medicine, serological analysis is used to detect viral hepatitis (B and C), as well as the causes of myocarditis, legionnaires' disease, atypical, intestinal infections.

Serological analysis is also used to diagnose autoimmune diseases. In this case, antibodies are produced to the tissues of the body itself and the study allows them to be detected.

Preparation for serological studies

Blood for serological analysis is taken on an empty stomach. Special preparation for the study is not required.