Lab Test

Hepatitis B Surface Antigen (HBsAg)

Test Codes

Antrim #31315, EPIC: LAB5222, HBSAG

Department

Chemistry

Specimen Collection Criteria

Collect (preferred specimen): One Gold-top SST tube. (Minimum Whole Blood: 4.0 mL)
Also acceptable: One Red-top tube. (Minimum Whole Blood: 3.0 mL

NOTE: Patient Preparation (Royal Oak ONLY): Twenty-four (24) hours before this test, the patient should not take multivitamins or dietary supplements containing biotin (Vitamin B7) which is commonly found in hair, skin and nail supplements and multivitamins.

Physician Office/Draw Specimen Preparation

  • Let SST specimens clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged SST tube within two hours of collection. (Minimum: 2.0 mL)
  • Let Red top specimens clot 30-60 minutes then immediately centrifuge to separate serum from cells. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F) within two hours of collection. (Minimum: 2.0 mL)

Preparation for Courier Transport

Transport: Centrifuged SST tube or serum aliquot, refrigerated (2-8°C or 36-46°F). (Minimum: 2.0 mL serum)

Rejection Criteria

  • Hemolyzed specimens.
  • Severely lipemic specimens.
  • Red-top tubes with serum not separated from cells within two hours of collection.

In-Lab Processing

Let SST specimens and Red-top tubes clot 30-60 minutes. Centrifuge SST, Red-top tubes, or Microtainers® to separate serum from cells. Deliver immediately to the appropriate testing station.

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers® with Separator Gel
Room Temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers® without Separator Gel
Room Temperature (20-25°C or 68-77°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 7 days

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Dearborn Chemistry Laboratory 
Farmington Hills Chemistry Laboratory
Royal Oak Automated Chemistry Laboratory

Performed

Sunday – Saturday, 24 hours a day.
STAT results (Labor and Delivery ONLY) available within 4 hours of receipt in the Laboratory.
Routine results available within 24 hours of receipt in the Laboratory.

Reference Range

Negative/Non-reactive.

Test Methodology

Chemiluminescence Immunoassay.

Interpretation

  • Non-reactive: No HBsAg detectable.
  • Reactive: Confirmatory testing will be performed on all positive specimens using neutralizing antibodies.
  • HBsAg detection methods are not sensitive enough to detect all potentially infectious units of blood or possible cases of hepatitis.
  • False-reactive results may be caused by particulate matter in the patient specimen, particularly fibrin clots and cellular material. Serum from heparinized patients may be incompletely coagulated and false reactives could occur due to the presence of fibrin on the reaction cell matrix. Draw serum prior to heparin therapy or draw specimen into a plasma collection tube to prevent this phenomenon.

Clinical Utility

  • HBsAg assay is used to aid in the diagnosis of hepatitis B, to monitor the status of infected individuals (i.e., whether the patient has resolved infection or has become a chronic carrier of the virus), and to evaluate the efficacy of anti-viral drugs. The CDC recommends a prenatal screening of all pregnant women so that newborns from HBV carrier mothers may obtain prophylactic treatment.
  • The incubation period for hepatitis B is approximately 70 days (range, 30 - 180 days). (1)
  • HBsAg appears in the serum 2-7 weeks before the onset of symptoms. It usually persists in the blood throughout the illness and disappears with convalescence. (1)

Clinical Disease

  • Patients with hepatitis B may present with fatigue, poor appetite, fever, vomiting and occasionally joint pain, hives or rash. Urine may become darker in color, and then jaundice (a yellowing of the skin and whites of the eyes) may appear. Patients may also be asymptomatic or experience only a few symptoms.
  • Hepatitis B infections (HBV) are found worldwide. It is the most prevalent type of acute hepatitis worldwide. Persistent infection with the virus is common. In highly endemic areas approximately 10% of the population are chronic carriers of HBV. The number of chronic carriers worldwide exceeds 230 million. (2)

Disease Reporting

This is a reportable infection and positive results will be reported to the Oakland County Health Department. For more information on reportable diseases, contact the Epidemiology Department at (248) 551-4040.

Transmission

Hepatitis B virus can be found in blood, saliva, semen and other body fluids of infected individuals. The virus is spread by direct contact with infectious body fluids. Transfusion was formerly the major mode of transmission of Hepatitis B. Hepatitis B infection is now most frequently spread by sexual contact, intravenous drug abuse and transmission from mothers to their newborn infants. (2)

Reference

  1. Hsu, H., Feinstone, S., Hoofnagle,J . Acute Viral Hepatitis in Mandell, G., Bennett, J., Dolin. R.(eds.), Principles of Infectious Diseases 7th edition New York,N.Y. 2005 Chapter 115,116.
  2. Farrar, W., Wood, M., Innes, J., Tubbs, H. Infectious Diseases, Time Mirror International Publishers Ltd New York, N.Y. 1995.

CPT Codes

87340
LOINC: 5195-3

Contacts

Last Updated

3/25/2022

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