[isk8n]

Hi,
I have a question regarding some terminology. What is the difference when a report says that a child is negative for Hepatitis B, but is positive for hbsag antibodies?

Any help would be greatly appreciated!
Thanks!
Valerie

[Alison_inPA]

Positive for HBsAg antibodies but negative for HBsAg itself means that the child is immune to hepatitis B, either through vaccination or through natural exposure to it.

That is good news!

[foxl]

On the other hand, in the event that the child is antigen-positive, it is best to test further, IN CASE there is also core antigen present.

[Alison_inPA]

foxl, I think you might be talking about core antibody, not antigen. I deal with hepatitis viruses extensively in my work, and I can tell you that even many medical professionals have trouble keeping these markers straight unless they deal with hepatitis B routinely.

If the child is HBs antigen positive, he/she is infected with hepatitis B no matter what the other markers indicate. Retesting later is required to see whether it's an acute (short-term) or chronic (long-term) infection.

If HBs antibody positive and HBs antigen negative, then he/she is immune to hepatitis B. Most US kids and kids from countries where infant vaccination is practiced will test this way because they've been immunized against HBV, but you can also acquire immunity from natural exposure.

Core antigen is not a standard blood test and would rarely be detected in the blood except by special procedures. Core antibody is a marker of current or past infection with HBV, and the only way to tell the differenct is to test for HBs antibody and HBs antigen.

A child who is Core antibody positive but negative for the HBs antibody and antigen has been exposed to HBV in the past but is not immune. In this case you'd probably want to test again in 6 months to make sure you're not missing a very early infection.

There are other markers that can help in interpretation as well. Feel free to PM me if you have questions.