Molecular testing for the hepatitis B virus is used to confirm chronic infection by this virus, to quantify the DNA of the virus in the serum of patients with chronic infection, and to monitor disease progression and response to antiviral therapy.
The diagnosis of acute or chronic hepatitis B virus (HBV) infection is based on the presence of serological markers such as hepatitis B virus surface antigen (HBsAg) and hepatitis B virus anti-HBc antibodies (anti-HBc IgM) or detection of virus DNA by molecular testing. Although the diagnosis of acute and chronic HBV infection is usually carried out by serological methods, detection and quantification of virus DNA are useful because it:
- May diagnose some cases of acute HBV infection very early and before the onset of HBsAg
- May distinguish active from non-active HBV infection
- Can monitor a patient's response to antiviral therapy
The presence of HBV DNA in the serum is a reliable indicator of active replication of the virus. Viral DNA levels are detectable 30 days after infection, reach their peak during acute hepatitis, and gradually decrease and disappear when the infection is brought under control. In cases of acute viral hepatitis with ambiguous or marginal HBsAg results, molecular testing for viral DNA in the serum is a useful test, as DNA can be detected approximately 21 days before HBsAg appears in the serum.
Patients with chronic hepatitis B fail to remove the virus and remain HBsAg positive. These cases can be classified as chronically active (high viral DNA levels, HBeAg positive) or chronically inactive (low or undetectable viral DNA levels, HBeAg negative). Serum viral DNA levels are useful in determining the status of chronic hepatitis B, by distinguishing between active and inactive cases. Patients with chronic active hepatitis B are at higher risk for more severe hepatic disease and are more infectious than patients with chronic inactive hepatitis B. Reactivation of inactive chronic HBV infection may occur with or without serum HBeAg reappearance. In these patients, detection of viral DNA is the only reliable indicator of active replication of the virus.
The therapeutic goal in HBeAg-positive patients is to achieve long-term suppression of virus replication with undetectable HBV DNA and loss of HBeAg seroconversion. The therapeutic target in HBeAg-negative patients is long-term suppression of the virus. The emergence of drug-resistant HBV strains is characterized either by the reappearance of viral DNA in the serum (after it had become undetectable) or by an increase in viral DNA levels (after the initial drop).
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.