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RE: [IP] Office A1C's vs. Labs Question

Shelly Tyler [mailto:email @ redacted] wrote:

> Hi I thought I better ask this again as we are heading for an 
> office visit in
> a few weeks.  I remember there was a thread on this topic but 
> wasn't sure what
> the concensus turned out to be...Which is more accurate?  The 
> A1C done via lab
> work or the one that they do with the machine at the office? 
> (Takes maybe 3
> minutes for results.) ALso which one gives a lower reading?  
> Does anyone know
> that?

Yes, someone does.  8-)

The difference is considerable.  The test done in a laboratory is a
moderate/high complexity test.  Specifically, it's a column
hemochromatography procedure (I think I have that right - if not it's very
close) that requires a highly trained technician who knows how to properly
handle the specimen, prepare it for the chromatograph, run the test, and
interpret the result.  Both the equipment and the technician have to pass
fairly rigorous proficiency testing up to three times a year.  The precision
on this test, when properly done, is around 98.5% (if memory serves). 

The rapid test done in the doctor's office is a waived test, meaning that
there is no proficiency testing required, the instructions must be
understood without assistance by someone with a seventh grade education,
most of the test is automated, and the results must be within 5% of a
standard (i.e. the aforementioned column chromatography) at least 50% of the
time (informally, the precision is +/- 20% or 60% precision).  This is the
same level of precision as our personal meters.

The test done in the doctor's office may be useful for screening or
obtaining a trend, but should not normally be used for diagnosis or

As a personal comment, there's probably nothing wrong with using the waived
test on most periodic visits, but I would request at least one per year be
sent out to be done by a lab using the standard test.

Jim Handsfield
mailto:email @ redacted OR
mailto:email @ redacted

The opinions expressed are my own and do not necessarily represent those of
my wife who runs this house and makes more important decisions than I do.
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