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Interpretive Handbook

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Test 88634 :
Hepatitis B Virus (HBV) DNA Detection and Quantification by Real-Time PCR, Serum

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Diagnosis of acute or chronic hepatitis B virus (HBV) infection is based on the presence of HBV serologic markers such as hepatitis B surface antigen (HBsAg) and hepatitis B core IgM antibody (anti-HBc IgM), or the presence of HBV DNA detected by molecular assays. Although the diagnosis of acute and chronic HBV infection is usually made by serologic methods, detection and quantification of HBV DNA in serum are useful to:

 

-Diagnose some cases of early acute HBV infection (before the appearance of HBsAg)

 

-Distinguish active from inactive HBV infection

 

-Monitor a patient's response to anti-HBV therapy

 

The presence of HBV DNA in serum is a reliable marker of active HBV replication. HBV DNA levels are detectable by 30 days following infection, generally reach a peak at the time of acute hepatitis, and gradually decrease and disappear when the infection resolves spontaneously. In cases of acute viral hepatitis with equivocal HBsAg test results, testing for HBV DNA in serum may be a useful adjunct in the diagnosis of acute HBV infection, since HBV DNA can be detected approximately 21 days before HBsAg typically appears in the serum.

 

Patients with chronic HBV infection fail to clear the virus and remain HBsAg-positive. Such cases may be further classified as chronic active (replicative) HBV (high HBV levels, hepatitis Be antigen [HBeAg]-positive) or chronic inactive (nonreplicative) HBV (low or undetectable HBV DNA levels, HBeAg-negative). HBV DNA levels in serum are useful in determining the status of chronic HBV infection, by differentiating between active and inactive disease states. Patients with chronic active HBV are at greater risk for more serious liver disease and are more infectious than patients with inactive HBV infection. Reactivation of inactive chronic HBV infection (HBeAg-negative state) may occur with or without reappearance of HBeAg in serum. In patients with HBeAg-negative disease, detection of HBV DNA is the only reliable marker of active HBV replication.

 

The therapeutic goal of anti-HBV therapy in patients who are HBeAg-positive is to achieve long-term suppression of viral replication with undetectable HBV DNA, HBe seroconversion and loss of HBeAg. The therapeutic goal in patients with HBeAg-negative disease is typically long-term viral suppression. The emergence of drug-resistant HBV strains (in response to treatment with nucleos(t)ide analogs, eg, lamivudine, adefovir, entecavir, tenofovir), is characterized by either the reappearance of HBV DNA in serum (after it had become undetectable) or an increase in HBV DNA levels (following an initial decline).

 

See HBV Infection-Diagnostic Approach and Management Algorithm in Special Instructions and HBV Infection-Monitoring Before and After Liver Transplantation in Special Instructions.

Useful For Suggests clinical disorders or settings where the test may be helpful

Confirmation of chronic hepatitis B virus (HBV) infection

 

Quantification of HBV DNA in serum of patients with chronic HBV infection (previously hepatitis B surface antigen-positive)

 

Monitoring disease progression in chronic HBV infection and/or response to anti-HBV therapy

Interpretation Provides information to assist in interpretation of the test results

The quantification range of this assay is 20 to 170,000,000 IU/mL (1.30-8.23 log IU/mL).

 

An "Undetected" result indicates that hepatitis B virus (HBV) DNA was not detected in the specimen.

 

A "Detected" result with the comment, "HBV DNA level is <20 IU/mL (<1.30 log IU/mL). This assay cannot accurately quantify HBV DNA below this level" indicates that the HBV DNA level is below the lower limit of quantification for this assay. When clinically indicated, follow-up testing with this assay is recommended in 1 to 2 months.

 

A quantitative result expressed in IU/mL and log IU/mL indicates the degree of active HBV viral replication in the patient. Monitoring HBV DNA levels over time is important for assessing disease progression or monitoring a patient's response to anti-HBV therapy.

 

A "Detected" result with the comment, "HBV DNA level is >170,000,000 IU/mL (>8.23 log IU/mL). This assay cannot accurately quantify HBV DNA above this level" indicates that the HBV DNA level is above the upper limit of quantification for this assay.

 

An indeterminate result with the comment "Inconclusive Result: Submit a new specimen for testing if clinically indicated" indicates that inhibitory substances may be present in the specimen. When clinically indicated, collection and testing of a new specimen is recommended.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

This test is not licensed by the FDA as a screening test for hepatitis B virus (HBV) infections or a diagnostic test to confirm the presence of HBV infection.

 

Laboratory evaluation of HBV infection status should begin with HBV serologic testing, including testing for the presence of hepatitis B surface antigen. A diagnosis of chronic HBV infection should not be based solely on the presence of detectable or quantifiable HBV DNA in a single serum specimen.

 

An "Undetected" HBV DNA test result in conjunction with a positive anti-HBV antibody status does not exclude the possibility of a resolved HBV infection. When clinically indicated, patients should be retested for HBV DNA in 1 to 2 months, to distinguish between past/resolved HBV infection and chronic HBV infection with episodic viral replication.

 

Quantitative HBV DNA results generated by this assay may be more than 0.5 log IU/mL lower than those of the VERSANT HBV DNA 3.0 Assay (bDNA) among some clinical serum specimens. Patient care providers are encouraged to use the same HBV DNA quantification assay for serial monitoring of HBV DNA levels in individual patient.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Undetected

Clinical References Provides recommendations for further in-depth reading of a clinical nature

1. Pawlotsky JM: Hepatitis B virus (HBV) DNA assays (methods and practical use) and viral kinetics. J Hepatol 2003;39:S31-S35

2. Servoss JC, Friedman LS: Serologic and molecular diagnosis of hepatitis B virus. Clin Liver Dis 2004;8:267-281

3. Goedel S, Rullkoetter M, Weisshaar S, et al: Hepatitis B virus (HBV) genotype determination by the COBAS AmpliPrep/COBAS TaqMan HBV test, v2.0 in serum and plasma matrices. J Clin Virol 2009;45:232-236

4. Chevaliez S, Bouvier-Alias M, Laperche S, et al: Performance of version 2.0 of the Cobas AmpliPrep/Cobas TaqMan Real-Time PCR Assay for hepatitis B virus DNA quantification. J Clin Microbiol 2010;48:3641-3647

5. Lok ASF, McMahon BJ: Chronic hepatitis B: Update 2009. Hepatology 2009;50:661-662


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