Very often when visiting a clinic, as well as before hospitalization, patients have to face the fact that in addition to a general blood test, biochemical tests, as well as tests for syphilis and HIV, the doctor also prescribes a blood test for HBsAg. What is it that few know. This study can also be prescribed by an infectious disease specialist, gastroenterologist, hepatologist, who diagnose liver diseases.
What is a HBsAg blood test? What are the indications for his appointment? What diseases can be diagnosed with this analysis? What will be the preparation for its delivery? You can find the answer to these and other questions in our article.
What is a HBsAg blood test?
This type of analysis is very common. Often it is taken for hepatitis B. This is the most popular, affordable, and also cheap type of study. It is due to its accessibility that this analysis is screening, that is, it is used during a mass examination, during a planned hospitalization of a patient, and is also prescribed among the decreed population.
Speaking about what it is, a blood test for HBsAg, it should be noted that this analysis is the most famous, among those that are carried out using modern technologies in the diagnosis of an infectious disease.
Previously, this analysis was done using a precipitation reaction, after which the method of immunoelectrophoresis and fluorescent bodies were used. To date, there is a third generation test system: radioimmunoassay, as well as enzyme immunoassay.
About hepatitis B virus
If the sterilization standards, as well as the treatments, had the ability to guarantee the destruction of the hepatitis B virus, then one would not have to think about other pathogens. They would be destroyed all. It is this virus that is currently the champion in the fight against disinfectants, as well as in resistance to external factors. This virus is not able to destroy even repeated freezing, as well as boiling. Even the effect of a weak acid is harmless to the hepatitis B virus. Although it should be noted that strong, inorganic acids can dissolve absolutely any tissue, however, they do not occur in our nature.
If the hepatitis B virus lies for 15 years in a freezer, where the temperature is minus 15 degrees, then it will still have the opportunity to infect a person. However, it is guaranteed that dry heat sterilization can destroy it, which will last for an hour at a temperature of about 160 degrees.
One of the structures of the virus that successfully resists all environmental factors is called HBsAG, or the Australian antigen. It is worthwhile to understand in more detail what the HBsAG blood test means.
What is this analysis talking about?
What does HBsAg show? HBsAg is a protein substance that is located on the surface of the shell of HBV, that is, the causative agent of hepatitis B. It is a surface antigen - a very dangerous substance foreign to the human body that causes an infectious disease.
You should also pay attention to the fact that there is another name for HBsAg - the Australian antigen. By the presence of surface antigen in the blood, the body identifies the main causative agent of the disease. After a certain period of time after infection, the processes of immune defense in the body begin to activate: the production of special antibodies to the HBsAg antigen, called Anti-Hbs, begins.
High Anti-Hbs in human plasma, the presence of the Australian antigen - an indicator of human infection with hepatitis B.
When is it necessary to take an analysis?
So, what the HBsAG blood test means is now clear. Screening for hepatitis B disease is required in the following cases.
- When working with blood: in gynecology, in the laboratory, in dentistry.
- When working in boarding schools, orphanages.
- When a woman becomes registered, and also before childbirth.
- When living with a person who has hepatitis B.
- With high rates of liver enzymes.
- With cirrhosis, as well as with other severe liver ailments.
- Before any surgical procedure.
- Before blood transfusion, as well as donating it to a donor.
- With venous drug addiction, as well as diseases that are transmitted sexually.
In addition, this analysis is necessary when observing the patient's symptoms that are characteristic of hepatitis B.
Training
So, now you know what the HBsAg blood test means, and also in what cases it is prescribed. But in order for the test results to be accurate, it is necessary to properly prepare for the analysis. For this, the patient must:
- refuse to use drugs 1-2 weeks before the test;
- do not drink alcoholic beverages, fried and fatty foods 2-3 days before the test;
- for two days to limit yourself in physical activity;
- quit smoking one day before testing;
- do not eat 12 hours before taking the test.
Also, pay attention to donate blood for analysis in the morning, from about 8:00 to 12:00. Strong tea and coffee before the study will have to be abandoned.
Diagnostics
How will an HBsAG blood test for hepatitis be performed? For testing, a specialist must take blood from a vein, it will take from 5 to 10 ml. The fence is standard: the hand above the elbow is pulled by a tourniquet, the skin and specialist hands should be treated with an antiseptic. The fence is carried out with a special disposable sterile syringe of the appropriate volume.
Following blood sampling, the following studies may be performed with this biomaterial.
- Radiological immune analysis. For this, antibodies are sent to a test tube, marked with radionuclides. During contact with a surface antigen, they begin to emit radiation, the intensity of which will be measured using a special device.
- Linked immunosorbent assay. For this, the collected blood is mixed with antibodies and dyes. If antigen is present in the blood, the solution will change color.
- Polymerase chain reaction. To do this, DNA infection is extracted from the biomaterial, and then DNA is detected and replicated, so that it is possible to determine the absence or presence of a disease in a patient, the genotype of the pathogen, as well as its amount in the blood.
It is important to note that the choice of a particular type of study will depend on the equipment of the laboratory and on the indications. The diagnostic method can be qualitative or quantitative. The first type provides information about the absence or presence of infection. Thanks to the second type, the amount of antigens in the patient's body can be determined.
Deciphering the result
Consider the decoding of an HBsAg blood test. Qualitative analysis for the detection of Australian antigen can be deciphered as follows:
- Positive result: “+”, “detected”, “positive.”
- Negative result: “-”, “not detected”, “negative.”
Quantitative analysis will be interpreted as follows:
- Positive - greater than or equal to 0.05 IU.
- Negative - less than 0.05 IU.
Positive result
HBsAg blood test positive, what does this mean? A positive result indicates the detection of antibodies against a surface antigen. This can be detected in the following conditions:
- chronic and acute hepatitis B;
- early transferred, but at the same time already cured disease;
- healthy carrier of the virus;
- vaccination against the virus.
In order to clarify the reason for the positive analysis, as well as to begin appropriate treatment, it is necessary to consult an infectious disease specialist or hepatologist. In addition, it may be necessary to carry out some additional studies, for example, elastometry and liver biopsy, blood biochemistry, testing for the total number of antibodies, quantitative PCR analysis.
Negative result
HBsAg blood test negative - what does it mean? A negative result is the norm, which indicates the absence of antibodies in the human body against HBsAg. This value will be observed if a person does not have hepatitis B, is also not a carrier of the virus and has never been vaccinated. However, the result of a HBsAg blood test for hepatitis may in some cases be erroneous, for example, in situations where:
- the immune system does not notice viruses and does not fight against them;
- hepatitis is present in the human body only in a latent form;
- blood sampling was carried out earlier than 2 weeks after infection.
Reason for false positive
Above we got acquainted with the features of the HBsAg HCV blood test, what it is, how is the preparation for the delivery of biomaterial carried out, what will be the decryption. However, in some cases, a false-positive result may be observed. But for what reasons is a positive result wrong? This can happen in the following cases.
- Before passing the analysis, the patient ignored the recommendations and advice of a specialist, that is, carried out incorrect preparation or did not conduct it at all.
- High body temperature, which can appear against the background of a developing infection in the body.
- The patient has a malignant and benign tumor.
- If a woman passes an analysis during pregnancy, then the result may be erroneous. This is especially true in cases where the collection of biomaterial is carried out in the third trimester of pregnancy.
- Autoimmune, as well as other pathological processes that occur in the patient's body.
- The use of certain drugs that have not been agreed with the doctor before taking the test.
- Also, very often there is a medical error, negligence of laboratory assistants, as well as a physical examination.
- Another common cause of error in testing is the inaccuracy of the analyzer with which the study was carried out.
To eliminate the possibility of false results, it is necessary to carry out another test test 2-3 weeks after the false analysis was received.
Little conclusion
Australian antigen quantitative or qualitative methods are currently determined in many private clinics, as well as in clinics and laboratories of state subordination. Such an examination is carried out only in the direction that the doctor should give the patient. State institutions carry out this analysis absolutely free of charge, however in this case there is a risk of receiving an unreliable false result. Paid blood tests for HBsAg HCV in private clinics and laboratories are performed using new, and sometimes innovative equipment, which leaves no chance for erroneous results.
Hepatitis B is a very dangerous viral disease, an accurate diagnosis will be extremely important. The key to getting rid of this virus is to pay close attention to your health, to follow all the recommendations of your doctor.