- Some statistics
- Characteristics of the virus and response changes in the patient's blood
- Who needs to be tested for hepatitis?
- How to determine hepatitis by immunological methods?
- The method of polymerase chain reaction (PCR)
- Express ways
- Indirect methods of detecting hepatitis
- Viral hepatitis A
- Viral hepatitis B
- Chronic hepatitis C
- Chronic hepatitis D
- What analyzes confirm toxic hepatitis?
- Do I need to prepare for testing for hepatitis?
- Related Videos
Hepatitis is an inflammatory liver disease. It is caused by viruses or substances with toxic effects. The disease turns off part of the liver function, which is even temporarily dangerous for the human body. Chronic course leads to cirrhosis with hepatic insufficiency, a cancerous tumor. That is why timely detection with the help of tests for hepatitis is so important for the appointment of treatment to the patient and prevention measures to others.
The incidence of hepatitis is increasing by 20-50% annually worldwide. The most common are hepatitis B and C. The fourth part of cases passes into incurable cirrhosis or liver cancer. 2017 is characterized by an outbreak of hepatitis type A in Europe.
In Russia, the incidence of type A has increased 2-fold compared to 2016. Maximum distribution was noted in Udmurtia, Irkutsk, Perm and Ivanovo regions. Rospotrebnadzor believes that for Russians the main reason is insufficient vaccination and low quality of drinking water.
Characteristics of the virus and response changes in the patient's blood
The causative agent of hepatitis is a virus that can not be detected in a conventional laboratory. In its specialized virological institutions, its properties have been studied. The microorganism consists of a protein coat. Sometimes it is additionally covered with a layer of fat. Inside the cell is its genome or material, which ensures the transmission of properties during reproduction and the ability to become infected.
It includes DNA and RNA chains. The products of the vital activity of the virus (proteins, polysaccharides, lipids) for the human body are foreign. In the immune reaction, they act as antigens. In response to the penetration of the hepatitis virus in the blood, antibodies are produced. They are represented by immunoglobulins:
- freely circulating through the circulatory system;
- associated with B-lymphocyte cells.
The study of blood tests for hepatitis made it possible to isolate viruses with different gene structures. To each of them, their own antibodies are developed (hepatitis markers). It turned out that in the clinical course and the expected damage to the liver, too, there is dependence on the genetic type of the virus. So, there are varieties of viral hepatitis, they are called the initial letters of the English alphabet.
To identify the presence of the virus in the human body, the most accessible are the immunological techniques for specific immunoglobulins or antibodies. Their presence also indicates the degree of activity or aggressiveness of the infection. Even to see the hepatitis virus under the electron microscope in specialized laboratories, it is necessary to pre-treat blood plasma with a special serum with antibodies.
Under the electron microscope around the virus, the "whisk" of the immune complexes differs, to improve its visibility it is contrasted with a solution of phosphoric-tungstic acid
Talking about the laboratory diagnosis of hepatitis, we will analyze the features of some immunological types of hepatitis diagnosis.
Who needs to be tested for hepatitis?
Hepatitis is dangerous for a long, asymptomatic period. Therefore, a test for this disease should be carried out first of all to people who are in contact with patients or blood. Of course, this group includes medical workers, especially those who work:
- in obstetrics;
- surgical departments;
- treatment rooms;
- at blood transfusion stations;
- dental offices.
The contingents responsible for donating blood for hepatitis also include:
- pregnant women;
- donors of blood and organs for transplantation;
- people from the patient's contact environment;
- patients of narcological and dermatological-venereological institutions;
- children from boarding schools, children's homes;
- people who have any planned operation.
Be sure to examine the hepatitis staff of laboratories, departments of hematology, hemodialysis
A special instruction defines diseases that require differential diagnosis with atypically occurring hepatitis:
- all chronic liver diseases;
How to determine hepatitis by immunological methods?
Identify the characteristic antigens, the composition of immunoglobulins antibodies help assays for markers of viral hepatitis. Their definition is carried out:
- in the blood serum;
- fecal masses;
- infected products;
- liver biopsy specimens.
The composition of antigens in the blood in hepatitis depends on the duration of the incubation period of the disease, the period that has elapsed since the infection. Various immunological diagnostic techniques are used. All immunological methods are based on the detection of antibodies or antigenic structures by labeled antibodies. Various modifications are applied.
Immunoenzyme analysis (ELISA) - the patient's serum is supplemented with standard antibodies labeled with enzymes. If there are antigenic structures of the virus, then the antigen is bound to the whey protein. The addition of a special colorant to the mixture changes its color in proportion to the number of molecules of the bound antigen. Thus, it is possible to obtain a quantitative reflection of the reaction.
Viral load in the results of studies is estimated in international units (IU / ml):
- high is the indicator - more than 800 IU / ml;
- low - below 800.
Immunoblotting - a more sensitive method, combines ELISA with electrophoresis. Identifies antibodies and immunoglobulins. First, the blood plasma of a patient with suspected antigens by electrophoresis in a gel medium is separated and transferred to a special paper impregnated with an activating agent. Serum is then applied and electrophoresis is performed.
In the arsenal of virology laboratories there are standard strips with antigens, it remains only to apply serum from the patient's blood
Depending on the material, the studies distinguish:
- DNA blotting;
Accounting for the length of time how much analysis is done for hepatitis by the method of immunoblotting shows the fluctuations from 1-3 hours to 1.5-2 days, depending on the task of the study.
Radioimmunological analysis (RIA) - differs from the previous two using isotopes to label one of the constituent components of the reaction. They are usually antigens. They are bound by plasma antibodies. Since the amount of the labeled isotope is known in advance, it is possible to quantitate the antibodies by radiometry of the samples. The technique is highly sensitive.
The method of polymerase chain reaction (PCR)
A diagnostic study is necessary, since it allows revealing even a small amount of DNA of the hepatitis virus. It is based on the process of copying DNA or RNA sites with gene information and drawing up chains. This helps increase the amount of substrate for analysis and conduct a full study of the type of virus.
Express tests in the form of strips, impregnated with a special substance, allow a qualitative reaction to markers of hepatitis by drop of blood from the finger. They are easy to use. According to experts, they are reliable enough for the initial diagnosis, they require only 15 minutes of time to get the result.
Express test systems for rapid inspection of contingents are issued
Indirect methods of detecting hepatitis
Laboratory diagnosis of viral hepatitis is the basis for identifying the disease. In addition to immunological tests, apply:
- a common blood test - characterized by an increase in ESR, hemoglobin;
- urine analysis for urobilin - positive;
- hepatic tests for the elucidation of functional disorders of the organ;
- puncture liver biopsy with the cytological analysis of the hepatic tissue.
Impaired liver function immediately manifests itself in biochemical studies of blood. Therefore, judging what tests should be submitted for hepatitis, it is not necessary to exclude the detection of metabolic disorders, changes in blood coagulability, hormonal composition. They are indirectly considered to be a witness in favor of hepatitis.
In the blood test for hepatitis must include specific enzyme assays of the liver:
- on alanine and aspartic transferase;
- alkaline phosphatase;
- lactate dehydrogenase;
- sorbitol dehydrogenase;
- gamma glutamntranspeptidase;
- gamma glutamyl transferase;
- fructose-1-phosphataldolase (F-1-FA).
The latter 2 - are considered to be the most organ-specific for liver damage. the remaining enzymes can give an erroneous result, as they increase in other diseases:
- with myocardial infarction;
- liver cancer;
- diseases of the pancreas;
- infectious mononucleosis;
- respiratory infections;
Biochemical blood indices confirming the functioning of the liver:
- timole sample;
- composition and ratio of proteins;
- Cholesterol, lipoproteins, triglycerides - reflect violations of fat metabolism;
- bilirubin - an indicator of the synthesis of pigments and gallbladder work;
- prothrombin index, fibrinogen - factors of blood coagulability.
Changes in biochemical tests do not differ in the trend for hepatitis caused by different viruses:
- increases aminotransferase, alanine more than aspartic, when recovered, the indicators are reduced;
- an increase in F-1-FA indicates the severity of damage to the liver tissue, this enzyme decreases before transaminases;
- in the urine bilirubin and urobilin are found;
- Thymol assay grows 3-5 times.
There is a release into the blood of enzymes, direct and indirect bilirubin. Decreased albumin, prothrombin index. Increased cholesterol, triglycerides.
Biochemical indicators of blood indicate the destruction of liver cells, a violation of the function of the organ and a change in all types of metabolism
Consider the diagnosis of examples of the most common forms of hepatitis. Types E, G and F are rare.
Viral hepatitis A
The disease differs from other types of infection by fecal-oral and acute course. The incubation period lasts from two weeks to 1.5 months. All close contact people are subject to inspection during this period. The cell's genome contains not RNA, but RNA (ribonucleic acid). Accordingly, when passing a blood or fecal analysis for hepatitis, it is necessary to expect markers of RNA structures.
The ELISA method reveals the characteristic antigen of the virus A (HAVAg) in the test material. It is found in the patients' stool for 7-10 days before the first clinical signs of the disease. The titer of antibodies to the IgM immunoglobulin grows in the acute phase of the disease even with an anemia and disappears after 6-8 months. Anti-immunoglobulins of type G are not diagnostic. The RNA of the virus (HAVRNA) is detected by PCR.
Viral hepatitis B
Inflammation of the liver takes immediately a chronic course. Doctors do not write "hepatitis b". The genome of the hepatitis B virus is formed by annular DNA. Transmitted parenterally (not through food, hands and contaminated foods).
Markers are defined as a specific antigen, and produced antibodies. Immunological studies reveal:
- HBsAg - Australian antigen, superficial, indicates an acute period of the disease, remains after recovery;
- Anti-HBs - antibodies to the Australian antigen, are detected when immunity to the virus;
- HBcAg - an antigen from the nuclear structure is found not in the blood, but in the liver tissues;
- Anti-HBc antibodies formed on a nuclear antigen indicate the degree of activity of the virus, the presence of antibodies to the anti-HBc IgM immunoglobulin confirms the exacerbation of hepatitis, high blood contagion, and Anti-HBc IgG is more characteristic for a favorable course;
- HBeAg - a protein in the core of the virus is regarded as an unfavorable sign, but antibodies to it Anti-HBe show a decrease in the activity of the virus.
The PCR method detects genetic material, the high content in the test indicates an active process, an exacerbation, a decrease is treated as a remission of the disease. The interpretation of the assay should be accompanied by a consideration of functional liver tests.
Chronic hepatitis C
The specificity of the hepatitis C virus lies in the content of gene information, as in the hepatitis A virus, not in DNA, but in RNA. This gives him a great opportunity to change (mutate). For the formation of antibodies and their determination, this property of the virus is a serious obstacle. Therefore, markers are:
- antiimmunoglobulin to type IgM - emphasize the acute phase of the disease, appears with ineffective treatment, is a sign of trouble;
- to IgG - confirm the presence of the virus, remain in the blood for life;
- HCV-RNA - the material of the virus genome, is evaluated by PCR results, even a weakly positive result confirms the presence of the virus in the body.
WHO recommends a triple PCR test for RNA of hepatitis C virus. The analysis was called test 321. Experts believe that only a triple confirmation for a viral load of at least 60 IU / ml can be considered a reliable diagnosis even in the absence of other markers.
Chronic hepatitis D
A feature of the hepatitis D virus is the lack of independence. It is completely dependent on the presence of the hepatitis B virus in the body. But according to the clinical course and infectiousness, it is considered to be the heaviest. The genome consists of a chain of RNA, so the virus also mutates as in hepatitis C.
Markers are obligatory:
- the aforementioned hepatitis B complexes;
- specific antigen HDAg;
- genetic material HDV-RNA;
- anti-immunoglobulins IgM and IgG.
The mutation occurs due to the replacement of different sections of the unstable RNA chain
What analyzes confirm toxic hepatitis?
Damaging factors with toxic effects on the liver can be poisonous substances of plant and artificial origin:
- inedible mushrooms;
- poisonous herbs, berries;
- production hazards (lead, mercury, heavy metal salts);
To detect the toxic nature of hepatitis is difficult. It is necessary to exclude all kinds of viral hepatitis, to take into account the anamnesis of the disease. The fact of inflammation and damage to the liver cells is confirmed by biochemical tests. Patients are assigned an expanded coagulogram to control the coagulation system and the degree of damage to the hepatic tissue.
Do I need to prepare for testing for hepatitis?
By giving blood to hepatitis on an empty stomach or not, a person can influence the final results of the study. After all, the doctor will prescribe the wrong treatment, using false information. Preparation includes the compulsory observance of several conditions:
- for 2 weeks before taking tests, you must stop taking any medications;
- it is impossible to carry out physioprocedures, ultrasound, X-ray examination;
- Before the day of taking the tests, it is necessary not to engage in intensive physical work and sleep well;
- in the diet should be excluded vegetables and fruits containing carotene (carrots, all fruits and berries yellow), alcohol, salt, fatty and spicy food;
- for several days will have to stop smoking;
- women should not take the test on a monthly basis;
- blood is taken on an empty stomach in the morning, you can not eat 10-12 hours before this time.
Receiving a referral to the laboratory, it is necessary to warn the attending physician about concomitant diseases, hypersensitivity to medications.
It is necessary to know in advance how many days the recommended analysis is done. Different techniques take from a few hours to 10 days. Difficulties in diagnosis require expectation of a result. Faster can be done in specialized institutions and private clinics, but it will not be expensive. A full examination allows you to assign the best therapy and monitor the course of treatment.