Hepatitis B virus, PCR-quantitative
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Why this test?
To predict the course of viral hepatitis B.
To confirm the chronic form of viral hepatitis B.
To identify carriers of viral hepatitis B and monitor the activity of virus reproduction.
To detect latent and mutant strains of the hepatitis B virus.
To assess the effectiveness of antiviral therapy for hepatitis B and to decide on further treatment tactics.
In what cases is it prescribed?
In acute and chronic viral hepatitis B.
With mixed hepatitis.
Before and during antiviral therapy.
Viral hepatitis B (HBV) is an infectious liver disease caused by the DNA-containing hepatitis B virus (HBV). Among all the causes of the development of acute hepatitis and chronic viral infection, the hepatitis B virus is considered one of the most common in the world. The true number of infected people is unknown, since many people have the infection without specific symptoms and do not seek medical help. The virus is often detected during preventive laboratory tests.
According to approximate estimates, about 350 million people in the world are affected by the hepatitis B virus and 620 thousand die annually from its consequences. The source of infection is a HBV patient or an asymptomatic virus carrier. HBV is transmitted through blood and other body fluids. It is possible to become infected through unprotected sexual contact, use of non-sterile syringes, blood transfusion and transplantation of donor organs, the child can be infected by the mother during or after childbirth (through cracks in the nipples).
The risk group includes: medical workers who may come in contact with the patient's blood, patients receiving hemodialysis, injection drug users, people who have a promiscuous sex life, children born to mothers with HBV.
The incubation period of the disease is from 4 weeks to 6 months. Viral hepatitis B can occur both in the form of mild forms that last for several weeks, and in the form of a long-term chronic infection.
The main signs of hepatitis: yellowness of the skin, fever, nausea, fatigue, in laboratory tests - impaired liver function and specific antigens of the hepatitis B virus. An acute disease can quickly lead to death, turn into a chronic infection or end in complete recovery. It is believed that persistent immunity is formed after HBV exposure.
Chronic viral hepatitis B is associated with the development of cirrhosis and liver cancer. There are several specific tests for the detection of existing or transmitted viral hepatitis B. To confirm the presence of infection and clarify the period of the disease, the determination of virus antigens, antibodies to them and DNA of the virus are used.
Polymerase chain reaction is characterized by high sensitivity and specificity. The DNA of the virus can be determined qualitatively or quantitatively by the PCR method. Thanks to the qualitative method, the presence of the hepatitis B virus in the body and its active reproduction is confirmed. Quantitative determination of the viral load makes it possible to assess the intensity of the disease, the effectiveness of the therapy or the development of resistance to antiviral drugs.
There is a dependence between the concentration of the virus in the blood and the result of acute viral hepatitis B. With a low level of viremia, the probability of the infection becoming chronic is close to zero, and the infected person is safe for others. With a high viral load (<105 copies / ml), chronicity occurs often and the patient is a potential source of infection. The relationship between the amount of viral DNA in blood serum, the presence of HBeAg, elevated ALT and the development of liver cirrhosis and hepatocellular carcinoma (liver cancer) has been proven.
The effectiveness of antiviral therapy is assessed by reducing the amount of viral DNA in the blood. 3-6 months after the start of treatment, the viral load with an adequate therapeutic response should decrease by 1-2 orders of magnitude. The absence of a decrease in the amount of the virus or its increase against the background of the treatment requires a review and change of therapy.
The quantitative determination of hepatitis B virus DNA together with the clinical picture of the disease and biochemical indicators, markers of infection, as well as the result of a puncture biopsy of the liver allows to give a prognosis of the disease and assess the need for antiviral therapy.