Re: Weird hepatitis B test results
- From: Robert1 <Goldentouchman@xxxxxxxxx>
- Date: Sat, 18 Aug 2007 12:01:46 -0700
On Aug 18, 10:26 am, ri...@xxxxxxxxx (Rich Wales) wrote:
"Robert1" wrote:
> 2. Might be distantly immune and test not sensitive enough
> to detect very low level of anti-HBs in serum. . . .
> The second possibility can be ruled out by a vaccine challenge
> and following the titer or strength of reaction after the
> first vaccine as mentioned. A rapid rise is indicative of an
> anamnestic response and thus a low level antibody titer was
> too low giving a negative HBsAB. A false positive would not
> yield a rapid or high titer after re challenge with vaccine
> and thus a true false positive.
Are you saying here that what really SHOULD have been done in my case,
in order to know for sure what was going on, is that I should have
been tested for anti-HBs after the first of my three vaccinations,
but before the second vaccination?
If one really wanted to know if it was a past infection, and in your
case the odds are fairly good that it was then yes that is an accepted
protocol that may detect such cases. The antibody pattern between
primary or secondary anamnestic response is different. On secondary
exposure the antibodies are geared up pretty quickly. It is typical
now for the actual antibody titer or concentration units being
reported with anti-HBs testing. I don't recall the cut-off titer now
but there is a protocol that I have read which is investigational by
nature.
And that if my anti-HBs had shot up right after the first vaccination,
that would mean that I had in fact had hepatitis B long ago -- so long
ago that my serum anti-HBs level was initially undetectable, but my
immune system would still have "remembered" the earlier infection and
would therefore have responded far more quickly to the first shot than
if I had never had the disease previously?
Yes. When dealing with acute vs old infection there are other
antibodies such as IgM which also denote a primary recent infection.
Anti-Hbcore IgM is used in acute hepatitis panels and not the total
Anti-HBc. IgG antibodies take time to generate and in some cases never
do meaning chronic hepatitis or non-immune state to hepatitis B.
Unfortunately, I wasn't able to get my medical clinic to do that extra
test -- and now that I've had the complete series of three shots, I
assume it's too late to do any useful test of this sort on me now.
But since the important thing is that I'm now confirmed to be immune,
it might not really matter too much.
Confirmation of protective antibody is always undertaken. It's too
late to determine whether you were exposed naturally or if the
antibody formation was a result of inoculation.
> The last one is of more concern and the reason why BB do what
> they do. It is possible to not only have low levels of HBsAg
> in serum present but in having genetic variants of the B surface
> antigen that will give a negative serology test in use for
> detection of HBs antigen.
So you're saying it's possible I might have been infected at some time
with a mutant variant of hepatitis B -- close enough to the normal
variety that the core antibody test was positive, but far enough from
the normal type that the surface tests were negative?l
Not very likely but protocols must include all possibilities to ensure
protection of the blood supply. In short if any testing is positive
then exclusion is undertaken whether it is a false positive or a true
positive. There are various distinct antigens of the hepatitis virus.
So, in effect, the "core" and "surface" tests done on me may actually
have been responding to two different strains of the virus -- one (a
variant) which I had indeed been exposed to, and another (the normal
type) which I had never been exposed to (at least not until I was
vaccinated against it last year)?
No, no as I was just explaining the possibilities and the testing
strategies involved. It wasn't one based on probabilities. It sounds
like a garden variety old infection with a low titer or non-existent
titer resulting in simply the presence of anti-HBs as David noted. It
can get confusing I know so deep in mind that antigens and antibodies
against those antigens are separate. There is HBs antigen and HBs
antibody. Testing for antibody to core antigen is in use. Antigen
testing involves the actual virus particle. In addition there are
tests for nucleic acid of the viral genomes.
And as a result, even though I never had the "standard" hepatitis B,
I may conceivably have been exposed at some time to a variant strain,
and I could pass this variant strain of hepatitis B along to someone
else, even though I'm clean and safe as regards the normal strain?
Not very likely in your case but only when all the remote
possibilities are undertaken. Keep in mind there is a window period
with acute infection in which serological testing may be negative and
thus the push for NAT nucleic acid testing.
Genetic variants of HBsurface antigen giving a negative HBsAg is
extremely rare and one for the literature. NAT can theoretically
eliminate that possibility. The position of the blood bank is to
exclude all potential risk and not necessarily investigate cases to
include people into the donor pool.
Would it be a prudent move for my wife to be tested for hepatitis B
exposure, then? If she also turns out to test positive for anti-HBc,
but negative on the other tests, what would be the best way to go from
there? And if any of the hep-B tests are positive for my wife, would
it be advisable for my children (who have both been vaccinated for HBV
but have, AFAIK, never had their exposure or immunity tested in any
way) to have further tests?
Family members of a household should be tested and yes test your wife.
It's unfortunate that children are not tested for antibody status to
see if the vaccine took hold or not. Booster shots have been given
taken periodically for hepatitis B but I am not sure there is any
established recommendations on how often or if they should be.
> As to blood units of type AB, donors in emergency and in those
> with massive transfusion needs are given type A blood. . . .
> the only area [type AB] donations would be wanted would be from
> males and not females who are Type AB for the plasma and those
> units are frozen for a year with a long half-life.
Could you elaborate a bit on this? Why is type-AB plasma wanted only
from men, and not from women?
Again one goes to safe practices in blood bank. Every year there are
about 50 fatal cases of transfusion related acute lung injury TRALI
occur in this country. Women because of babies and antigenic exposure
can develop white cell antibodies that may agglutinate white cells in
donors and cause lung injury. The switch to having only males donate
the plasma reduces the incidence of TRALI dramatically. This will
happen in a couple of years for all plasma of all blood types.
Rich Wales ri...@xxxxxxxxx http://www.richw.org
*DISCLAIMER: I am not a doctor. My comments are for discussion pur-
poses only and are not intended to be relied upon as medical advice.
.
- References:
- Weird hepatitis B test results
- From: Rich Wales
- Re: Weird hepatitis B test results
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