Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1370 page)

   Positive results (quantitative anti-HBs levels of ≥12 mIU/mL) indicate an adequate immunity to hepatitis B from previous HBV infection or HBV vaccination.

   Screen for individuals at high risk for exposure, such as hemodialysis patients, persons with multiple sex partners, persons with a history of other STDs, IV drug abusers, infants born to infected mothers, individuals residing in long-term residential facilities or correctional facilities, recipients of blood- or plasma-derived products, allied health care workers, and public service employees who come in contact with blood and blood products.

Decreased In

   Inadequate immune response to HBV vaccination.

   Limitations

   Passively acquired anti-HBs (i.e., transfusion of whole blood or plasma, recent immune globulin treatment) can yield positive results without indicating permanent immunity to HBV infection.

   Anti-HBs levels from previous hepatitis B or HBV vaccination may fall below detectable levels over time.

   Not useful for diagnosis of acute HBV infection. Does not differentiate between vaccine-induced immunity and immunity after recovery from hepatitis B infection without further tests like hepatitis B core total antibodies.

   Coexistence of HBsAg/HBsAb reported in 24% patients. In most cases, the antibodies are unable to neutralize circulating virions. These are regarded as carriers.

HEPATITIS B SURFACE ANTIGEN (HBsAg)

   Definition

   Serologic hallmark of HBV infection. First serologic marker to appear (1–10 weeks of acute exposure). Patients who subsequently recover; undetectable after 4–6 months. Persistent for >6 months in chronic infection.

   
Normal range:
Negative.

   Use

   Diagnosis of acute, recent, or chronic hepatitis B infection. Determination of chronic hepatitis B carriage.