Hepatitis B virus (HBV) surface antigen - serum or plasma specimen
- Synonyms: HBsAg, Hepatitis B Virus Surface Antigen
- LIS Mnemonic: HBVSAG
Collect
PREFERRED: Serum is the preferred specimen. Collect blood in a 4 ml Gold Serum Separator Tube-Clot Activator & Gel.
REMARK: Plasma is an acceptable alternative specimen. Blood can be collected in plastic tubes containing dipotassium EDTA with or without gel separator.
Volume Required
4 ml of blood
Minimum Required
2 ml of blood
Transport
A total of 2-4 ml of blood (for every 2-3 Hepatitis and HIV tests ordered) should be collected.
For the CHOP enterprise, submit blood specimens as soon as possible at room temperature to Central Laboratory Services.
For outside clients, it is recommended that serum or plasma specimens be removed from the clot, red blood cells, or separator gel as soon as possible after collection and before shipping specimens. When shipping serum or plasma specimens, package and label specimens in compliance with applicable state, federal, and international regulations covering the transport of clinical specimens and infectious substances. Specimens may be shipped at 2-8C (wet ice) or frozen (dry ice). Do not exceed the storage time limitations listed under the heading of Stability.
Stability
Serum or plasma specimens should be stored for no longer than 3 days at room temperature or 7 days at 2-8C following specimen collection and separation from clot, red blood cells, or separator gel. If a storage period greater than 7 days is anticipated, serum or plasma should be stored frozen at -20C or colder. No more than 3 freeze-thaw cycles should be performed on any sample prior to testing, and specimens should not be stored in frost-free freezers.
Unacceptable conditions
Do not use serum or plasma specimens that are heat-inactivated, pooled, grossly hemolyzed, or contain obvious microbial contamination. Performance has not been established for the use of cadeveric specimens or the use of boody fluids other than human serum or plasma.
Specimen Handling
Unprocessed blood specimens should routinely be refrigerated at 4C upon arrival in the laboratory. One should remove the serum or plasma from clotted blood, red blood cells, or separator gel as soon as possible to avoid hemolysis. The best results are generally observed for serum or plasma specimens that are clear and nonhemolyzed. Lipemic, icteric, or hemolyzed specimens should be avoided when possible, and specimens with obvious microbial contamination should not be used. Specimens containing unremoved clots, red blood cells, or particulate matter may give inconsistent results and should be clarified by centrifugation before testing.
Days Performed
Monday thru Friday
Reported
Daily
Reflex Testing
Hepatitis B surface antigen confirmation assay. All specimens that test repeatedely positive for Hepatitis B surface antigen by the screening immunoassay must be confimed by a neutralization assay.
CPT
87340 (initial screening),87341 (confirmation assay, if necessary)
Methodology
Chemiluminescent microparticle immunoassay
Disease Information
Utility:
A test for HBsAg is indicated as an aid in the laboratory diagnosis of acute, chronic, or resolved hepatitis B viral infection. Detection of HBsAg indicates the presence of HBV but does not distinguish between acute and chronic infection. During acute HBV infection, HBsAg appears 3-5 weeks before the onset of symptoms, peaks during the acute phase of the disease, and slowly declines to undetectable levels within 4-6 months. Persistance of HBsAg for 6 months or longer after acute illness is indicative of chronic infection. HBsAg can be detectable for life in most chronically infected individuals; only 1-2% of chronic HBV carriers become negative for HBsAg each year. The HBsAg assay also may be used to test for HBV infection in pregnant women. Prenatal testing has been recommended so that newborns from mothers who are HBV carriers may receive appropriate prophylactic treatment.
Interpretation
HBV surface antigen is the earliest indicator of the presence of acute infection; it is also indicative of chronic infection. A hepatitis B core IgM antibody test and an HBV core total antibody (IgG & IgM) test should also be ordered to help differentiate acute from chronic HBV infection. Negative results for HBsAg indicates no evidence of a recent or chronic infection with HBV. This does not exclude the possibility of exposure to or early acute infection with HBV. If clinically indicated, please wait 1-2 weeks and submit another specimen for additional HBV surface antigen testing. A hepatitis B core IgM antibody test may also be ordered on the current and repeat specimens. Patients with possible HBsAg mutations may be nonreactive for HBsAg. If acute or chronic HBV infection is suspected, and the HBsAg result is nonreactive, it is recommended that other HBV serological markers and HBV DNA be tested to confirm the HBsAg nonreactivity. For diagnostic purposes, HBsAg reactivity should be correlated with patient history and the presence of other hepatitis markers.
Reference Values
Negative or non-reactive for hepatitis B Virus (HBV) surface antigen
Remarks
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