HB cAB results and exposure window
Jan 28, 2007
I donated blood two weeks ago and received a letter from the blood center that my HB sAG results were non-reactive but that the HB cAB results were positive (they don't test for HB sAB). The letter indicates that I may have been exposed to Hepatitis B and it has cleared my system or that the test may have been a false reactive. The epidemiologist said their tests are highly sensitive and that things such as stress or some medications might create a false reactive on the HB cAB. I looked over my records and I had taken Vicodin the night before my blood donation but had forgotten. Could this have caused a false reactive on the HB cAB.
Also, I had donated blood in May 2006 and not tested positive for anything on the Hepatitis testing they routinely run. I had unprotected sex about 18 weeks before this last blood donation that resulted in a positive HB cAB. My partner had unprotected sex 7 months earlier. Is it possible that I could have been exposed through him via his previous unprotected sexual encounter with the other party?
After exposure, how long does it take for the body to register a reactive result for HB cAB? And how long will the blood continue to register reactive even in the absence of a positve HB sAG test?
I've just had independent blood labs started but won't get the results for a week. I'm very confused over what the epidemiologist said, what I'm reading on line, etc., etc.
Thank you in advance for your response.
Response from Dr. McGovern
There are several things that can cause a false positive.
The only important issue is to have a full hepatitis B panel test to determine your true test results.
False positive tests occur in about 5 percent of blood donors in general, so this occurs more often than you would expect.
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