IgM Antibody to hepatitis A

(Anti-HAV IgM or HAV IgM Ab)

• Positive result defines a recent HAV infection.
• May be negative in early infection (if collected within 5 to 7 days after onset of symptoms)
• Present for 3 to 6 months after onset of acute infection.

Total antibody to hepatitis A

(Anti-HAV Ab or HAV Ab)

• Of extremely limited value in the diagnosis of acute infection.
• Positive result indicates past infection and immunity to HAV.
• Individuals given serum immune globulin for HAV prophylaxis may test as positive for at least six months.

Hepatitis B surface antigen

(HBsAg)

• Used to diagnose an acute or chronic infection.
• First marker to appear in an acute infection.
• Disappearance indicates recovery from infection.
• Persistence for > 6 months indicates chronic infection (carrier).
• Individuals tested within 72 hours after administration of the vaccine may test as positive. (See anti-HBs, anti-HBc IgM and HBeAg.)

Antibody to hepatitis B surface antigen

(Anti-HBs or HBs Ab)

• Only test which can be used to assess presence of protective immunity after immunization with hepatitis B vaccine.
• Levels of 10 MIU/mL (10 IU/L) are usually considered protective.  Routine monitoring of levels in individuals who have received the complete course of vaccine is not considered necessary.
• Some individuals, e.g. healthcare workers, who are believed to have been exposed to the virus by a needlestick injury, should have their anti-HBs levels tested to determine whether they require administration of hepatitis B immune globulin (HBIG) and hepatitis B vaccine booster.
• Positive result in individuals with recent acute HBV infection indicates convalescence.
• Usually NOT detected when HBsAg is also present.
• In some cases of chronic hepatitis B infection, both HBsAg and anti-HBs can be detected.  These antibodies are heterotypic and likely not protective.
• Antibody levels may decline with time.

IgM antibody to hepatitis B core antigen

(Anti-HBc IgM or HBc IgM Ab)

• This test is expensive and should primarily be used if there is a high index of suspicion to indicate that the patient is in the early convalescence “window period” (2 to 16 weeks post infection) when HBsAg has disappeared and anti-HBs levels are not yet detectable.
• Positive result in patients who are also HBsAg positive usually indicates acute infection.
• Usually detectable for 3 to 12 months.
• Depending upon the threshold level of sensitivity, low levels may be detected in patients with chronic infection and reactivation.

Hepatitis B e antigen

(HBeAg)

• Marker of active HBV replication.
• Also a marker of infectivity. However, the absence of HBeAg in a person who is HBsAg-positive does not imply that the individual is NOT infectious.
• Can be used to monitor therapy of patients with chronic HBV infection.

Antibody to hepatitis B e antigen

(Anti-HBe or HBe Ab)

• Appears as HBeAg disappears.
• In chronic hepatitis B infection, a positive result indicates resolving or minimal liver disease.
• However, individuals who are HBsAg-positive and have anti-HBe present must still be considered infectious.

Total antibody to hepatitis B core antigen

(Anti-HBc or HBc Ab)

• A positive result indicates past infection with hepatitis B virus.
• Usually persists for life.
• This antibody is absent in individuals who are immune solely as a result of vaccination.
• Up to 10% false-positive rate has been described in individuals with no documented infection to HBV.  If uncertain, presence of one other marker, e.g., anti-HBs or anti-HBe would confirm previous exposure with HBV.  Alternatively a negative repeat test later may indicate an earlier false-positive result.

Hepatitis B viral DNA

(HBV DNA)

• Available by special request only.  Of very limited value in the diagnosis of HBV infection.
• Used to determine the presence of HBV DNA circulating in the blood which is a measure of virus replication in the liver.
• Primary use is in monitoring treatment and clarifying some complex situations.

Antibody to hepatitis C

(Anti-HCV or HCV Ab)

• Enzyme immunoassay (EIA) tests are the most common screening tests used to detect antibody.
• With present EIA tests, a reactive result may be obtained after 8 to 12 weeks to several months following infection with HCV.  Earlier generations of EIA tests often gave negative antibody results for up to 1 year.
• False-positive results are found in patients with autoimmune chronic active hepatitis, alcoholic liver disease and other disorders relating to hypergammaglobulinemia.
• Presence of antibody can be due to acute or chronic infection.  It may represent only evidence of an infection with HCV.
• Persistently elevated ALT levels suggest chronic infection.  Repeatedly normal levels do not exclude chronic infection, but suggest low grade inflammation.
• ALT values in some patients with HCV infection are within normal ranges.

Recombinant immunoblot for antibody to hepatitis C

(RIBA)

• Supplementary test for the verification of EIA reactive results to HCV.
• Indeterminate results may be found in early seroconversion, immunosuppressed patients or those unable to mount a complete antibody response.  Some of the conditions which give false-positives in the EIA may well give an indeterminate or non-specific result in the RIBA.

Polymerase chain reaction for hepatitis C

(PCR for HCV)

• Available by special request only, as it is a research tool.
• Used to determine the presence of HCV RNA circulation in the blood which is a measure of virus replication in the liver.
• Can be used to assess the infectivity of the patient and monitor therapy.
• May be of use in early infection when antibody to the virus is undetectable, and in immunocompromised patients who may not seroconvert.
• Can be of use in resolving indeterminate RIBA results.

Antibody to hepatitis D virus

(Anti-HDV or HBV Ab)

• HDV occurs as a co-infection with HBV or super-infection of a chronic HBsAg carrier.
• Antibodies appear late during the course of acute infection.
• HDV is uncommon in Alberta.

Antibody to hepatitis E virus

(Anti-HEV or HEV Ab)

• Routine tests not presently available for detection of this agent.
• This test may be available by special request only from reference laboratories.

ALT

alanine aminotransferase

• Liver enzyme test
• Used to assess extent of liver inflammation
• Can be used to monitor resolution of inflammation following acute or chronic infection