Hepatitis B surface antigen (HbsAg) may be detected in the presence of acute or chronic hepatitis B virus infection [ 458 ]; it indicates that the person is infectious. In acute infection, its appearance predates clinical symptoms by 4 weeks, and it remains detectable for 1–6 weeks. The tests for detecting hepatitis B and D disease are primarily serologic and molecular ( Table 59 ). Clinicians should check the clinical laboratory test catalog or consult with the performing laboratory on the minimum volumes of blood needed, as some molecular assays require more blood than others for testing.
Table 59.
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Laboratory Diagnosis of Hepatitis B and D
Abbreviations: HBV, hepatitis B virus; HDV, hepatitis D virus; IgG, immunoglobulin G; IgM, immunoglobulin M; PPT, plasma preparation tube; RT, room temperature; SST, serum separator tube.
The presence of hepatitis B surface (HBs) antibody indicates recovery from and immunity to hepatitis B infection, as a result of either natural infection or vaccination. In most patients with self-limited acute hepatitis B infection, HbsAg and HBs antibody are not detectable simultaneously in serum or plasma.
Hepatitis B core (HBc) IgM antibody appears during acute or recent hepatitis B virus infection and remain detectable for about six months. A serologic “window” occurs from 6 to 8 months after infection when HbsAg disappears and HBs antibody becomes undetectable. During this “window” period, infection can be diagnosed by detecting HBc IgM antibody.
HBc total antibodies appear at the onset of symptoms of acute hepatitis B infection and persist for life. Their presence indicates acute (positive HBc IgM antibodies), recent (positive HBc IgM and HBc total antibodies), or previous (positive HBc total antibodies but negative HBc IgM antibody) hepatitis B virus infection.

Their presence indicates acute (positive HBc IgM antibodies), recent (positive HBc IgM and HBc total antibodies), or previous (positive HBc total antibodies but negative HBc IgM antibody) hepatitis B virus infection. There is currently no commercially available test for HBc IgG antibody in serum or plasma.
A chronic hepatitis B virus carrier state is defined by persistence of HbsAg for at least 6 months. In patients with chronic hepatitis B, the presence of hepatitis B e antigen (HbeAg) in serum or plasma is a marker of high viral replication levels in the liver. Loss of HbeAg and emergence of antibody to hepatitis B e antigen (ie, Hbe antibody) is usually associated with improvement of underlying hepatitis and a reduction in the risk of hepatocellular carcinoma and cirrhosis. Alternatively, disappearance of HbeAg may denote the emergence of a precore mutant virus; high concentrations of HbsAg and HBV DNA, in the absence of hepatitis B e antigen and presence of Hbe antibody suggest the presence of an HBV precore mutant virus. Hepatitis B viral DNA is present in serum or plasma in acute and chronic hepatitis B infection [ 459 ]. Quantification of HBV DNA in serum or plasma may be included in the initial evaluation and management of chronic hepatitis B infection, especially when the serologic test results are inconclusive or when deciding treatment initiation and monitoring patient's response to therapy. Other molecular laboratory tests used in the diagnosis and management of chronic hepatitis B infection have been reviewed in the published literature and include assays for determining viral genotype, detection of genotypic drug resistance mutations, and core promoter/precore mutations [ 459 ].
Detection of HBs antibody in the absence of HBc total antibodies distinguishes vaccine-derived immunity from immunity acquired by natural infection (in which both HBs antibody and HBc total antibodies are present).

Diagnosis of acute or chronic HBV infection requires serologic testing (Table 5). Because HBsAg is present in both acute and chronic infection, presence of IgM antibody to hepatitis B core antigen (IgM anti-HBc) is diagnostic of acute or recently acquired HBV infection. Antibody to HBsAg (anti-HBs) is produced after a resolved infection and is the only HBV antibody marker present after vaccination. The presence of HBsAg and anti-HBc, with a negative test for IgM anti-HBc, indicates chronic HBV infection. The presence of total anti-HBc alone might indicate acute, resolved, or chronic infection or a false-positive result.

HBsAg,Total anti-HBc,IgM anti-HBc,Anti-HBs,HBV DNA,Interpretation
-,-,-,-,-,Never infected
+,-,-,-,+ or -,Early acute infection; transient (up to 18 days) after vaccination
+,+,+,-,+,Acute infection
-,+,+,+ or -,+ or -,Acute resolving infection
-,+,-,+,-,Recovered from past infection and immune
+,+,-,-,+,Chronic infection
-,+,-,-,+ or -,"False-positive (i.e., susceptible); past infection; “low-level” chronic infection; or passive transfer of anti-HBc to infant born to HBsAg-positive mother"
-,-,-,+,-,Immune if anti-HBs concentration is ≥10 mIU/mL after vaccine series completion; passive transfer after hepatitis B immune globulin administration

Serologic markers for HBV infection include HBsAg, antibody to HBsAg (anti-HBs),
immunoglobulin class M (IgM) antibodies to hepatitis B core antigen (IgM
anti-HBc), and immunoglobulin class G (IgG) anti-HBc (IgG anti-HBc) ( 49 , 65 , 66 ). At least one serologic marker is present
during the different phases of infection. HBV DNA is a measure of viral load and
reflects viral replication ( 49 ) ( Table
1 ). Hepatitis B e antigen (HBeAg) can be detected in persons with acute
or chronic HBV infection; the presence of HBeAg correlates with viral
replication and high infectivity; antibody to HBeAg (anti-HBe) correlates with
the loss of replicating virus, although reversion to HBeAg positivity can occur
( 7 ).

Individuals with chronic HBV infection should be evaluated to determine the phase of infection and for the presence of liver inflammation and fibrosis (Figure 2). In addition to a comprehensive history and physical, the following blood tests should be obtained: HBV DNA level by quantitative polymerase chain reaction assay, complete metabolic panel, complete blood cell count, and serological testing for HBeAg and anti-HBe.

Because levels of ALT and HBV DNA fluctuate during the immunoactive phases, differentiating between these phases and the inactive chronic HBV phase requires serial measurements (at least every 3 months for ≥1 year). Additional items for consideration when evaluating a patient with chronic HBV infection appear in Box 2 .

Quantitative HBV DNA

HBV e antigen (HBeAg) and HBV e antibody (anti-HBe)

Screening for HIV, hepatitis C virus, hepatitis A virus immunity

Complete blood cell count

Complete metabolic panel (glucose, electrolytes, assessment of renal and liver function, including measurement of liver enzyme level)

Liver biopsy

Transient elastography

If either of the above is not available, a blood test should be used (types of blood tests include: FibroSure, FIB-4 [a score based on levels of aspartate aminotransferase {AST} and alanine aminotransferase and age], and APRI [AST-to-platelet ratio index]) b

Hepatocellular carcinoma screening with ultrasonography, computed tomography, or magnetic resonance imaging

Hepatitis A vaccine

a Defined as 2 positive test results for HBV surface antigen measured at least 6 months apart.

a Defined as 2 positive test results for HBV surface antigen measured at least 6 months apart.

b Cutoffs for advanced fibrosis (including cirrhosis based on FIB-4 and APRI scores) were originally validated among patients with chronic hepatitis C virus and HIV co-infection. The validity of the same cutoffs for patients with chronic HBV infection are unclear.

Figure 2:
Caption: Phases of Chronic Hepatitis B Virus (HBV) Infection
Description: Chronic HBV infection is divided into 4 phases. Patients transition between phases (ie, better and then worse or worse and then better). Not all patients will go through all of these phases. Some patients may transition through the phases rapidly such that distinct phases may not be discerned in clinical practice. Alternative nomenclature refers to phases of chronic HBV infection without intrahepatic inflammation and fibrosis as chronic infection, and those phases with intrahepatic inflammation and fibrosis as chronic hepatitis. Only 6% to 10% of adults older than 40 years who acquired chronic HBV infection perinatally remain positive for HBeAg. Anti-HBe indicates HBV e antibody; ALT, alanine aminotransferase.aThe upper limit of normal for ALT level was defined by the American Association for the Study of Liver Diseases as 19 IU/mL for women and 30 IU/mL for men.bThe immunoactive and immunoreactive phases may occur with ALT levels within 2 times the upper limit of normal.