What is a serological blood test? Serology What is a serological blood test?

Serological blood analysis is a fundamental research method carried out in order to quickly and reliably identify microbes, infections and viruses in the human body. In addition, thanks to this method, it is possible to determine the entire list of existing diseases that have arisen as a result of decreased immunity.

Through serological analysis, blood taken from the patient is examined for HIV, syphilis and other dangerous ailments. In addition, the study is necessary in case of confirmation of the patient’s blood type and to determine the specificity of proteins.

As noted earlier, the analysis is recommended for diagnosing infectious diseases and establishing the stage of the inflammatory process. Thanks to a serological chemical reaction, it is possible to determine the level of interaction between antigens and antibodies responsible for the result.

This analysis applies:

  1. When determining the number of antibodies that fight the causative agent of the disease: during the analysis, blood serum is mixed with the antigen of the causative agent of the disease, after which they look at the reaction that occurs.
  2. The opposite situation is that a developing infection is detected due to existing antigens detected by adding antibodies to the blood.
  3. In case of blood type determination.

In case of poor blood clotting and in case of hypercoagulation, dangerous consequences associated with cardiac activity can occur.

The need for serological tests increases when the patient is suspected of having sexually transmitted infections and other diseases. The resulting analysis contains information about the presence of antibodies to a given type of bacteria or virus in the blood. These are liver diseases, measles, human immunodeficiency virus, herpes, etc. If antibodies are detected, the doctor makes a conclusion for the patient and determines the further course of therapy. If necessary, additional studies will need to be completed.

The material is collected from the ulnar vein. The analysis is taken on an empty stomach in the morning. However, before taking a biochemical test for hepatitis, all brightly colored vegetables and fruits should be excluded from the daily diet. If confirmation of the results of the completed analysis is required, a secondary examination can be prescribed without special preparation.

Interpretation of serological analysis

This laboratory test is indicated for patients when difficulties arise in the differential diagnosis of various types of infections. In this case, only a serological analysis can determine the type of infectious agent and help the doctor determine the diagnosis of the disease. In addition, the enormous benefit of this technique is reflected in the selection of drug therapy for the patient, because the causative agents of many diseases differ greatly in their sensitivity to the action of antibiotics and other drugs.

Thanks to a serological test, it is possible to easily determine whether a person has a disease that was caused by a latent infection entering the body. Having completed the procedure for collecting material, laboratory assistants decipher the indicators, allowing experienced doctors to fully examine the pathologies that have arisen in the body. If there are no antibodies in the blood, a person does not develop an infectious disease. In this case, the result of the analysis will be positive. But this is a rare case. As a rule, in the presence of symptoms of the disease, serological analysis serves as evidence of the presence of a dangerous pathology. In this case, the process is duplicated. Initially, the presence of small infectious agents in the body is detected. Next, the degree of development of the inflammatory process is identified by the number of antibodies.

The norm for this test is considered to be zero antibody levels. The value will always mean the presence of pathology in the body. In this regard, the patient needs to undergo additional studies to confirm the diagnosis.

Features of serological testing for syphilis, HIV and hepatitis

The test for syphilis involves the detection of proteins responsible for the entry into the human body of the infectious agent - Treponema pallidum. The biological material in this case is blood serum. Before donating blood, you should stop taking heart medications and avoid any alcoholic beverages 4 days before donating blood. It should be noted that infection can only be established after 1.5-2 months from the moment of infection. If a pregnant woman performs this test, she should be prepared for a false positive result.

The following symptoms may be the basis for conducting a serological test for hepatitis:

  • causeless fatigue and weakness of the body;
  • poor appetite or lack thereof;
  • vomit;
  • changes in the color of urine and feces;
  • yellowness of the facial skin.

In addition, diagnosing hepatitis is considered necessary during a medical examination or during examination during pregnancy.

If a person has been tested positive for HIV infection, this does not mean that he is infected with AIDS. If less than 2 months have passed since infection, the presence of antibodies to the immunodeficiency virus in the blood cannot allow us to draw a conclusion indicating the development of the disease. To do this, you need to repeat the procedure. HIV testing is mandatory during pregnancy at the time of the first visit and at 30 weeks of pregnancy.

Enzyme immunoassay blood test

One of the popular types of serological studies is considered to be an enzyme-linked immunosorbent assay, which is carried out to effectively control the number of antigens and antibodies in human blood serum. In addition, using this method it is possible to determine the content of hormones, immunological complexes and other biological components.

When bioorganic substances penetrate into human tissue and vital organs, immunity prevents them from affecting health due to antibodies and immunoglobulins. As a result of their influence, an antigen-antibody complex is formed in the body. Only its comprehensive analysis will be an important component of the enzyme immunoassay method.

The main material required to perform the study is the patient’s blood. In some cases, in order to recognize the type of disease or select therapy, cerebrospinal and amniotic fluid is taken for analysis. Enzyme immunoassay blood test as a component of serology is based on a detailed study of blood molecules and immunoglobulins. Their feature is the ability to detect and destroy infectious agents together with a specific antigen.

The advantages of this method include the ability to determine the disease in the early stages of its development, the speed and accuracy of the result, low cost and the elimination of preparation for the study.

There are few disadvantages of the method: it is possible to obtain a false negative result, which requires further re-testing.

Before taking any laboratory test, you must follow the preparation rules. The collection of material must be carried out exclusively in sanitary conditions. In addition, it is necessary to prevent foreign substances from entering the blood. An important condition for every infection test is to donate blood exclusively on an empty stomach. At the same time, the day before the test, it is not recommended to consume fatty and spicy foods, alcoholic beverages and sweet drinks. Additionally, it is necessary to avoid stressful situations and any physical activity. In any case, before deciding to donate blood for testing, you need to undergo a medical examination by your attending physician.

Having heard the patient’s complaints, the doctor will be able to recommend the advisability of taking a serological blood test.

Diagnosis is the most important step in the treatment of any disease. Depending on the correct diagnosis is not only successful treatment, but also the opportunity to prevent the development of complications and associated pathologies. What is serological testing? This is a method of diagnostic analysis of a patient's biological sample for the presence of antibodies and antigens. The test allows you to identify dozens of diseases, the phase of the disease and monitor treatment.

Why is the study prescribed?

This type of medical research is widely used in various fields of medicine. The complement fixation reaction or CFR is aimed at identifying specific cells in the blood serum, antibodies that the body produces to fight infections and viruses.

An isoserological study is aimed at determining the patient’s blood type, Rh factor and other blood parameters.

  • Serological blood tests are used in gynecology to detect sexually transmitted diseases. Serological titration is also used for a comprehensive examination of expectant mothers (toxoplasmosis, HIV, syphilis, etc.). When registering pregnant women, this is a mandatory test.
  • In pediatrics, serological tests are used to confirm the diagnosis of “childhood” diseases (chickenpox, rubella, measles, etc.) if the symptoms are not pronounced and it is not possible to determine the disease based on clinical indications.
  • Serological tests allow venereologists to quickly and accurately make a diagnosis. For similar symptoms and complaints, a blood test can detect antibodies to syphilis, giardiasis, ureplasmosis, chlamydia, herpes and other diseases.
  • Gastroenergologists, hepatologists and infectious disease specialists use serological blood tests to diagnose viral hepatitis.
  • A physician may suspect any infectious or viral disease. For confirmation, serological reactions to specific antibodies in the body are used. An analysis is carried out for encephalitis, brucellosis, whooping cough, Dengue virus, immunodeficiency virus, allergies, etc.
  • Serological diagnosis for hospitalization plays an important role. This diagnostic method can show what stage of development the disease is at, and whether immediate hospitalization is required or outpatient treatment is sufficient.

A sample of saliva and feces can be used as a biological material for research, but the patient’s venous blood is most often used. Tests for serological tests should be taken from the cubital vein in a laboratory setting. Before taking the test, you should consult with your doctor and prepare.

Preparing for analysis

This type of research is carried out in both municipal and commercial institutions. It is better to make a choice in favor of the laboratory that has the most modern equipment and has only positive reviews about its work. For busy patients, the laboratory can provide blood collection services for RBC at home.

In this case, the patient does not have to waste time on the road, and queues are eliminated.

Preparation for venous blood collection includes several general rules. Before the test, you should not eat food, that is, the test is taken on an empty stomach. When donating blood, you need to be in a state of calm and not worry. Before the procedure, you should not undergo other procedures (x-rays, ultrasound, etc.). A few weeks before blood sampling, medications should be discontinued in consultation with the attending physician. Some recommendations depend on the disease for which the test is being performed. For example, when testing for hepatitis, fatty foods and alcohol are excluded from the diet 2 days before the test.

Fluorescence reaction

One of the types of serological reactions is fluorescence or RIF. This research method is carried out using a reagent that highlights the desired antibodies in the blood serum. To perform a direct serological reaction or PIF, specific antibodies are marked with a fluorescent substance. This is the fastest type of research, which is carried out in one stage.

Another method, called indirect or RNIF, is carried out in 2 stages. In the first, specific cells (antibodies) do not have fluorescent labels, and in the second, appropriately labeled antibodies are used to detect the antigen-antibody complex. The glow reaction appears only after contact with a specific antibody. The result of the manipulations is assessed by a special device that evaluates the intensity of radiation and also determines the shape and size of the objects under study. The infectious agent is determined with 90-95% confidence, depending on the type and stage of the disease.

Linked immunosorbent assay

For ELISA studies, serological reactions are carried out using unique stable reagents. Labeled substances are attached to a specific (desired) type of antibody. As a result, serology provides a qualitative or quantitative assessment from a patient's blood sample. If the substrate does not have pronounced markers, the result is considered negative. In the case of a qualitative study, a positive result means only the presence of antibodies in a biological sample.

Serodiagnosis with quantitative determination of antibody cells provides a more complete picture. Based on the amount of detected cells, the doctor can tell whether the disease is in the initial stage, acute, or is it an exacerbation of the chronic form of the disease. When making a diagnosis, the patient’s clinical picture and complaints are also taken into account.

Research Features

When testing for brucellosis, blood serum is monitored for self-retention without antigen. This allows you to increase the reliability of the test. The result of the test for brucellosis can be positive, negative or unexpressed, that is, questionable. If questionable results are obtained, repeated blood sampling is recommended. Brucellosis is also diagnosed based on the results of blood cultures, bone marrow and cerebrospinal fluid examinations.

Advantages and disadvantages of serology

Diagnostics using serological methods is widely used in modern medicine. This test is especially relevant when identifying viral and infectious diseases. The same type of tests is used in geographic screening and health surveys to prevent epidemiological outbreaks.

Serological tests have a number of advantages.

  • Any type of serological test has high reliability.
  • Serology tests are carried out quite quickly. The result of the RSC is known within 24 hours, and you can get it via the Internet without leaving your home. In special cases during hospital treatment, the test is carried out within several hours.
  • RSC allows you to monitor the development of the disease and monitor the effectiveness of the treatment.
  • Serological research methods are low cost and available to patients.

Serological tests also have some disadvantages. In order for the examination to provide the most reliable information, the blood test should be carried out taking into account the incubation period of the disease.

Herpes simplex types 1 and 2 can be determined only 2 weeks after infection, and testing for the immunodeficiency virus is carried out 1, 3 and 6 months after contact with the patient.

The reliability of the study may be affected by human factors. If the patient neglects the rules for preparing for the study or the laboratory technician makes an error in processing the blood sample, a false or questionable result may be obtained. This situation occurs in approximately 5% of cases. As a rule, the attending physician, based on clinical indications, easily calculates the RSC error.

Serological blood testing is a modern and reliable way to detect such dangerous diseases as HIV, hepatitis, brucellosis, STDs, etc. This section of medicine is aimed at studying human blood plasma and its immunological properties. The serological method is widely used, and the cost of research in private laboratories is relatively low. To carry out the analysis, modern equipment is used, which minimizes the influence of the human factor on the research results.

In contact with

To identify most diseases, you need to take various blood tests, which will help determine not only the presence of a dangerous pathology, but also determine the effectiveness of treatment. A serological blood test is a common laboratory research method that will determine whether there are viruses, infections and microbes in the human body. This examination can identify diseases that occur when the body’s defense reactions are weakened; it will help determine the presence of even such a dangerous disease as HIV.

What is serological analysis

In medicine, serology is a branch of the science of immunology that studies the reaction of antigens to antibodies. This branch of medicine studies blood plasma, as well as its immunological capabilities. A blood test for serological reactions determines the presence and behavior of special antibodies that the human body produces to fight various infections and viruses. He will most likely identify the disease and determine the success of treatment.

Where do antibodies come from and what are they needed for? The human body is constantly exposed to various viruses and infections. To combat them, our immune system produces special antibodies that bind infectious antigens and suppress their activity. A serological blood test will report on the state of a person’s immune system and indicate the presence of infectious viral diseases in the present time or those that the body has already gotten rid of.

A serological blood test, unlike a blood test, must be taken if you suspect any viral or infectious disease. This study will determine the exact causative agent of the disease in cases where it is difficult to make a correct diagnosis. If the pathogen is correctly identified, the most effective treatment can be prescribed.

In what cases is this study prescribed? If you need to determine the number of antibodies that act on a virus or infection that provokes a disease. To do this, the pathogen antigen is introduced into the blood plasma, after which the results of the process are studied.

It is possible to carry out the opposite process: the presence of infection is detected by adding antibodies to the blood plasma, which makes it possible to determine the presence of antigens and their belonging to a specific microorganism.

Also, using this study, a person’s blood type is determined.

Blood tests - serological tests must be carried out if sexually transmitted diseases are suspected, as well as to make a diagnosis if sexually transmitted diseases are suspected.

The interpretation of this analysis will provide information about the presence of antibodies in the blood plasma to a specific group of dangerous microorganisms. Those who are prescribed this study may have a question: what does a serological blood test show, what diseases can be determined with its help? The list of diseases that should be diagnosed using the serological method is actually quite long. The study will identify diseases such as herpes, rubella, syphilis, hepatitis, toxoplasmosis, measles, typhoid fever, giardiasis, whooping cough, etc.

Moreover, the study will help identify autoimmune diseases and determine not only the blood type, but also the Rh factor. It is also carried out to confirm paternity and determine the nature and source of infection in epidemics. This test is mandatory for a pregnant woman to be examined for the presence of diseases dangerous to the fetus, such as toxoplasmosis, syphilis, rubella, etc.

How to take a serological blood test

Features of the serological test

Blood is collected for serological testing only a few weeks after the suspected infection. If you try to conduct the examination right away, it will give false results. Confirmation of infection can only be obtained a month and a half after the attack.

Another feature of this method is the likelihood of a false positive result in some cases. For example, during pregnancy you can get a false positive result for hepatitis. Sometimes a test can reveal the presence of HIV infection, while in fact the body is not susceptible to such a disease. A positive result obtained during the initial analysis is not the ultimate truth. As a rule, the study is almost always repeated to make an accurate diagnosis.

Decoding the research results

After taking blood and conducting a study, the specialist first identifies the presence of an infectious or viral disease in the human body, and then, based on the number of antibodies, determines the degree of development of the disease. If a serological blood test is carried out, the transcript of which shows zero antibody content, then the body is not infected. But if the antibody content is slightly higher, most likely there is a viral or infectious disease. But we remember that a re-analysis is necessary.

Cost of serological blood test

Such important research must be carried out in a safe place, because your health depends on it. The test can be done either in a regular clinic or in a specialized paid medical center. If you are planning to conduct a test in a paid clinic, pay special attention to finding a suitable center where professionals work. Choose a laboratory with a long track record and one that has been around for many years. Pay attention to patient reviews of a particular medical center, choose the one for which you will collect the most positive reviews. At the same time, you should not trust the responses found on the Internet; it is better to ask your friends about professional laboratories. It is better to trust information received from a specific person with whom you know personally.

Prices for serological blood tests can vary greatly. The cost is influenced by the expected disease, the diagnosis of which is necessary and the location. On average, prices for research start at 300 rubles, and the upper limit can exceed 3,000 rubles.

A serological blood test is one of the laboratory diagnostic methods that allows us to identify the infectious process in the child’s body and the degree of its development. The results of this study are based on the degree of interaction between antibodies and antigens. So, by conducting such an analysis, our specialist can determine whether antibodies to certain viruses or bacteria are present in the child’s body, including hepatitis, HIV infection, etc. If such antibodies are detected, our doctor makes a preliminary diagnosis and prescribes clarifying examinations.

A serological blood test is used for the following purposes:

  • identifying the amount of antibodies to specific infectious pathogens. To do this, pathogen antigens are added to the blood serum;
  • the analysis can also be carried out using the opposite algorithm, when pathogen antibodies are added to the blood serum to determine its antigens;
  • determination of blood group.

In addition to a diagnostic study of a small patient, a serological blood test can be prescribed by our doctor to assess the effectiveness of the treatment, as well as after completion of the therapeutic course.

Preparing for a serological blood test

Blood for serological testing is taken from a vein in the morning on an empty stomach. Older children should not be given fatty foods before the test. If the test is carried out to detect viral hepatitis, two to three days before the test it is necessary to avoid consuming any brightly colored fruits, vegetables, and juices.

It is important to remember that a negative serological test result does not provide a 100% guarantee that the disease is not present in the body. If the doctor has doubts about the reliability of the results, he may order a repeat test in a few days.

Infectious diseases initiate the production of appropriate antibodies in the blood of a sick person. This is how the body's immune defense works.

Determining the presence of antibodies to a specific virus or bacteria makes it possible to find out about the onset of a disease before its main symptoms appear. Today, serological tests provide the most complete picture. Therefore, in this article we will talk about serological testing.

What are serological tests

Methods for studying biological materials of people and animals that can detect antibodies or antigens in them that the body produces as a protective reaction in the fight against infections are called serological studies. Such methods are used to determine the causative agent of infection, as well as for the purpose of:

  • determination of blood group,
  • studying immunity through determining the level of its humoral component,
  • determination of tissue antigens.

Who is it prescribed to?

Why do it?

The method is valued by specialists as a way to make a high-quality diagnosis of the disease.

  • If the patient is at the stage of the disease, then repeated studies are recommended to be carried out at intervals of approximately a week in order to monitor the effectiveness of the treatment used.
  • Serological tests are often used to determine which pathogen caused the disease after the patient has suffered it.

Types of procedure

Serological research methods are based on various reactions:

  • Neutralization reaction relies on the property of immune serum antibodies to act as a neutralizing agent against toxins or microorganisms themselves, preventing their damaging effects.
  • Agglutination reaction, which, in turn, is divided into the following subtypes:
    • direct reactions - they are used to test blood serum for the presence of antibodies. Killed microbes are added to the composition being studied, and if a precipitate appears in the form of flakes, it means that the reaction to this type of microbe is positive;
    • the indirect hemagglutination reaction is carried out by introducing into the blood serum erythrocytes on which antigens are adsorbed; these agents interact with the same kind of antigens present in the blood serum, resulting in a scalloped precipitate.
  • Reaction involving complement used to detect infectious diseases. The method is implemented through the activation of complement and observation of the reactions occurring in the medium under study.
  • Precipitation reaction is carried out by layering an antigen solution onto a liquid medium - immune serum. The antigen used for this method is soluble. The reaction is that the antigen-antibody complex undergoes precipitation; the resulting precipitate is called precipitate.
  • Reaction using labeled antigens and antibodies is based on the fact that microbes or tissue antigens, processed in a certain way, acquire the ability to emit light under the influence of ultraviolet rays. The method is used not only for diagnosing antigens, but also for determining medicinal substances, enzymes, and hormones.

Contraindications for

Due to the fact that the method involves studying the patient’s biological material, it cannot have a negative impact on humans. Therefore, there are no contraindications for use.

The study is completely safe.

We will describe below how a serological test is carried out.

Indications for testing

The method is used to determine the causative agent of infection, including for the following diseases:

  • HIV infection,
  • toxoplasmosis,
  • infectious diseases acquired through sexual contact;
  • diphtheria,
  • Availability ;
  • brucellosis,
  • staphylococcal infections,
  • hepatitis.

The method is also used to identify the following diseases:

  • opisthorchiasis,
  • amoebiasis,
  • cysticercosis,
  • giardiasis,
  • pneumonia.

Preparation for the procedure

No special preparations are required for the procedure. One condition must be observed: blood sampling is done on an empty stomach.

The algorithm for sampling (taking) blood (material) for serological testing is described below.

Carrying out analysis

Blood is drawn from the ulnar vein. In order for the study to work, blood is drawn not with a syringe, but by gravity. A needle without a syringe is inserted into a vein and up to 5 ml of blood is collected in a test tube.

During the procedure, the patient experiences slight discomfort as the needle is inserted into the vein. The subsequent steps are not at all worrying.

The interpretation of the results of a serological blood test is described below.

Decoding the results

The results obtained should be considered in conjunction with the clinical picture of the disease, checking the suspected diagnosis using several tests. This is due to the fact that the tests are specific and sometimes do not have absolute sensitivity to infectious diseases.

The price for a comprehensive serological blood test is described below.

Average cost of the procedure

The price of the procedure will depend on the type of study. It consists of the cost of the analysis and the cost of antibodies to a specific pathogen. The average cost of the procedure is within 700 rubles.

Serological reactions are described in the video below: