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- Hepatitis-associated Antigen
Test blood donors (HBsAg positive individuals are rejected). Hepatitis B surface antigen is the earliest indicator of the presence of acute infection. Also indicative of chronic infection. Test is useful in the differential diagnosis of hepatitis.
Patients who are negative for HBsAg may still have acute type B viral hepatitis. There is sometimes a “core window” stage when HBsAg has become negative and the patient has not yet developed the antibody (anti-HBs). On such occasions, both tests for anti-HBc are usually positive and anti-HBc, IgM is the only specific marker for the diagnosis of acute infection with hepatitis B. In cases with strong clinical suspicion of viral hepatitis, serologic testing should not be limited to detecting HBsAg, but should include a battery of tests to evaluate different stages of acute and convalescent hepatitis.
Immunochemiluminometric assay (ICMA)
Hepatitis B virus (HBV) is a DNA virus with a protein coat, the surface antigen (HBsAg) and a nucleic acid core, the core antigen (HBcAg). There are eight different serotypes. Early in infection, HBsAg, HBV DNA, and DNA polymerase can all be detected in serum.
HBsAg can be detected one to seven weeks before liver enzyme elevation or the appearance of clinical symptoms. Three weeks after the onset of acute hepatitis, about 50% of patients will still be positive for HBsAg, while at 17 weeks only 10% are positive. The best available markers for infectivity are HBsAg and HBeAg. The presence of anti-HBs is frequently associated with noninfectivity. The chronic carrier state is indicated by the persistence of HBsAg and/or HBeAg over long periods (six months to years) without seroconversion to the corresponding antibodies. Such a condition has the potential to lead to serious liver damage, but may be an isolated asymptomatic serologic phenomenon.
Persistence of HBsAg, without anti-HBs, with combinations of positivity of anti-HBc, HBeAg, or anti-HBe indicates infectivity and need for investigation for chronic persistent or chronic aggressive hepatitis. See figure in Hepatitis B Core Antibody, IgM .
Serum or plasma
1.5 mL (Note: This volume does not allow for repeat testing.)
If tube other than a gel-barrier tube is used, transfer separated serum or plasma to a plastic transport tube.
Causes for Rejection
This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.
|Order Code||Order Code Name||Order Loinc||Result Code||Result Code Name||UofM||Result LOINC|
|006510||HBsAg Screen||5196-1||006510||HBsAg Screen||5196-1|
|Reflex Table for HBsAg Screen|
|Order Code||Order Name||Result Code||Result Name||UofM||Result LOINC|
|Reflex 1||016105||HBsAg Confirmation||016105||HBsAg Confirmation||7905-3|