Very often when visiting the clinic, as well as before hospitalization, patients have to deal with the fact that in addition to the general blood test, biochemical studies, as well as tests for syphilis and HIV, the doctor also prescribes a blood test for HBsAg. Only a few know what it is. This study can also be prescribed by an infectious disease doctor, gastroenterologist, hepatologist who diagnose liver diseases.
What is an HBsAg blood test? What are the indications for its 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 an HBsAg blood test?
This type of analysis is very common. Often it is taken for viral hepatitis B. This is the most popular, affordable, and also the cheapest type of study. It is due to its availability that this analysis is screening, that is, it is used for mass examination, withplanned hospitalization of the patient, and also appointed among the decreed population group.
Speaking of 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 diagnosing any infectious disease.
Previously, this analysis was done using the precipitation reaction, after that the method of immunoelectrophoresis was used, as well as fluorescent bodies. To date, there is a third-generation test system: radioimmunoassay, as well as enzyme immunoassay.
About the hepatitis B virus
If sterilization and processing standards had the ability to destroy the hepatitis B virus with guarantee, then one could not think about other pathogens. They would all be destroyed. It is this virus that currently holds the record for the fight against disinfectants, as well as for resistance to external factors. This virus is not able to destroy even repeated freezing, as well as boiling. Even exposure to a weak acid is harmless to the hepatitis B virus. Although it should be noted that strong, inorganic acids can dissolve absolutely any tissue, they do not occur in nature.
If the hepatitis B virus lies for 15 years in a freezer where the temperature is minus 15 degrees, it will still have the ability to infect a person. However, dry heat can be guaranteed to destroy it.sterilization, which will last for an hour at a temperature of about 160 degrees.
One of the structures of the virus that successfully resists all factors from the external environment is called HBsAG, or the Australian antigen. It is worth understanding in more detail what the HBsAG blood test means.
What does this analysis say?
What does HBsAg show? HBsAg is a protein substance that is located on the surface of the HBV membrane, that is, the causative agent of hepatitis B. It is a surface antigen - a very dangerous, foreign substance for 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 a 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, which are called Anti-Hbs.
High Anti-Hbs in human plasma, the presence of the Australian antigen is an indicator of human infection with hepatitis B.
When should I get tested?
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 laboratory conditions, in dentistry.
- When working in boarding schools, orphanages.
- Whenbecoming a woman in a position for registration, as well as before childbirth.
- When living with a person who has hepatitis B.
- When liver enzymes are high.
- With cirrhosis, as well as with other severe liver ailments.
- Before any surgical procedure.
- Before a blood transfusion, as well as donation by a donor.
- With venous drug addiction, as well as diseases that are sexually transmitted.
In addition, this analysis is necessary when a patient has symptoms that are characteristic of hepatitis B.
Preparation
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. To do this, the patient needs:
- refuse to use medicines 1-2 weeks before the test;
- do not consume alcoholic beverages, fried and fatty foods 2-3 days before the test;
- restrict yourself in physical activity for two days;
- quit smoking one day prior to testing;
- do not eat 12 hours before the test.
Also note that you need to donate blood for analysis in the morning, from about 8:00 to 12:00. Strong tea and coffee will have to be discarded before the study.
Diagnostics
How will the HBsAG blood test for hepatitis be performed? Fortesting, a specialist must take blood from a vein, it will take from 5 to 10 ml. The fence is standard: the arm above the elbow is pulled with a tourniquet, the skin and hands of a specialist must be treated with an antiseptic. The sampling is carried out with a special disposable sterile syringe of the appropriate volume.
After blood sampling with this biomaterial, the following studies can be carried out.
- Radiological immunoassay. For this, antibodies are sent to a test tube, marked with radionuclides. During contact with the surface antigen, they begin to emit radiation, the intensity of which will be measured using a special device.
- Immunoassay. For this, the collected blood is mixed with antibodies and dyes. If an antigen is present in the blood, the solution will change color.
- Polymerase chain reaction. To do this, DNA of the infection is isolated from the sampling biomaterial, and then the detection and replication of DNA is carried out, thanks to which it is possible to determine the absence or presence of the disease in the patient, the genotype of the pathogen, as well as its amount in the blood.
It is important to note that the choice of a specific type of research 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, it is possible to determine the amount of antigens in the patient's body.
Deciphering the result
Let's considerinterpretation of the HBsAg blood test. Qualitative analysis for the detection of the Australian antigen can be deciphered as follows:
- Positive result: "+", "detected", "positive".
- Negative result: "-", "not found", "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 is positive, what does that mean? A positive result indicates the detection of antibodies against the surface antigen. This can be found in the following conditions:
- chronic and acute hepatitis B;
- early transferred, but already cured disease;
- he althy carriage of this virus;
- vaccination against the virus.
To clarify the reason for a positive test, as well as to start appropriate treatment, it is necessary to consult an infectious disease specialist or a hepatologist. In addition, some additional studies may be needed, for example, elastometry and liver biopsy, blood biochemistry, testing for the total number of antibodies, quantitative PCR analysis.
Negative result
HBsAg blood test is negative - what does it mean? A negative result is the norm, which indicates the absence of antibodies against HBsAg in the human body. This value will be observedin the event that a person does not have hepatitis B, and is not a carrier of the virus and has never been vaccinated. However, a blood test result for HBsAg hepatitis can be erroneous in some cases, for example, in situations where:
- the immune system has not noticed viruses and is not fighting 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 the preparation for the delivery of the biomaterial is carried out, what the decoding will be. However, in some cases, a false positive result may be observed. But for what reasons is a positive result erroneous? This can happen in the following cases.
- Before taking the test, the patient ignored the recommendations and advice of a specialist, that is, he did the wrong preparation or did not do it at all.
- High body temperature, which may appear against the background of a developing infection in the body.
- The patient has a malignant and benign tumor.
- If a woman is tested during pregnancy, 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 medicines that have not beenagreed with the doctor before taking the test.
- Medical error, laboratory negligence, and medical examinations are also very common.
- Another common cause of error in testing is the inaccuracy of the analyzer with which the study was carried out.
To rule out the possibility of false positives, another test should be performed 2-3 weeks after a false positive was obtained.
Small conclusion
Australian antigen is currently being determined by quantitative or qualitative methods in many private clinics, as well as in public clinics and laboratories. Such an examination is carried out only in the direction that the doctor must issue to the patient. Government agencies perform this analysis absolutely free of charge, but in this case there is a risk of obtaining an unreliable false result. Paid HBsAg HCV blood tests in private clinics and laboratories are carried out using new and sometimes innovative equipment, which leaves no chance for erroneous results.
Hepatitis B is a very dangerous viral disease, accurate diagnosis will be extremely important. The key to getting rid of this virus is to pay close attention to your he alth, to follow all the recommendations of your doctor.
