What does a reactive Hepatitis A (Hep A) antibody total and a reactive Hepatitis B (Hep B) surface antibody indicate, and what is the significance of no Hepatitis C (Hep C) core or surface antibodies in a 29-year-old male?

Interpretation of Hepatitis A and B Serology Results

A reactive total hepatitis A antibody and reactive hepatitis B surface antibody indicate past infection with hepatitis A virus and immunity to hepatitis B virus (either from vaccination or past infection), while the absence of hepatitis C antibodies suggests no exposure to hepatitis C virus. 1, 2

Hepatitis A Antibody (Total) Reactive

• This finding indicates that the 29-year-old male has been previously infected with hepatitis A virus (HAV) or has been vaccinated against it.
• Total anti-HAV includes both IgM and IgG antibodies:
  • If this was a recent infection, IgM anti-HAV would be positive
  • In resolved past infection or vaccination, only IgG anti-HAV would be positive 1
• This result confirms the patient has protective immunity against future HAV infection 2

Hepatitis B Surface Antibody (Anti-HBs) Reactive

• A reactive hepatitis B surface antibody (anti-HBs) indicates immunity to hepatitis B virus (HBV) 1, 2

• This immunity could have developed through:

  1. Previous HBV vaccination (most common cause in a 29-year-old)
  2. Recovery from past HBV infection 2

• To distinguish between immunity from vaccination versus past infection, testing for hepatitis B core antibody (anti-HBc) would be helpful:

  • If anti-HBc is negative: Immunity is from vaccination
  • If anti-HBc is positive: Immunity is from past infection 2

No Hepatitis C Antibodies

• The absence of hepatitis C core or surface antibodies indicates that the patient has not been infected with hepatitis C virus (HCV) 1
• This is a reassuring finding, as HCV infection can lead to chronic liver disease in approximately 75-85% of infected individuals 3

Clinical Significance

• The patient has protective immunity against both hepatitis A and B viruses, which is beneficial as:

  • Acute hepatitis A or B in patients with underlying liver disease can cause more severe hepatic injury 3
  • Coinfection with multiple hepatitis viruses increases morbidity and mortality 2, 3

• Important points to explain to the patient:

  1. He is protected against hepatitis A and B infections
  2. No evidence of hepatitis C infection
  3. No need for hepatitis A or B vaccination 2
  4. His immune status should be documented in his medical record for future reference

Potential Pitfalls

• Rarely, anti-HBs may be passively acquired (e.g., after recent administration of blood products), which would not indicate true immunity 4

• In some cases, isolated anti-HBc positivity (if tested) without detectable HBsAg or anti-HBs can occur in:

  • The "window period" of acute hepatitis B
  • Resolved infection with waned antibodies
  • Low-level chronic infection
  • False positive results 2, 5

• If there are risk factors for hepatitis C, consider repeat testing in the future, as antibodies may take up to 12 weeks to develop after infection 1