| Backhand 2005-01-27, 8:51 am |
| On or about Sun, 23 Jan 2005 07:41:42 GMT someone/thing calling
him/her/itself "Nicole H" <crimsonshedemonREMOVE@hotmail.com> inked
the following:
>Explanation of how the ANA titer is obtained
>I don't understand how the titer could be positive but below detectable
>limites... doesn't make sense to me. The sample needs to be diluted or it
>doesn't... dilution determines the titer.
I don't know if there are two different methods being employed - 1
using fluorescence to qualitatively analyze the sample and then a
second (different) method to actually determine the concentration of
antibodies
or
2 - The same fluorescence method is used twice, first the qualitative
one and then a single dilution 40 fold and a reassessment. If this is
the case then that *could* explain a positive indication with a report
of <= 1:40 in concentration.
But I am not certain of the exact methodology - why is 1:40 the lowest
number? Is it because there is a second method being employed that
cannot report concentrations lower than corresponding to this dilution
factor or is it simply the same method being used a second time and
for some reason the very first step is a 40 fold dilution instead of
some other number, like 10?
The report states "ANA SCREEN - POSITIVE" and "ANTINUCLEAR ANTIBODIES
<1:40". There is some (apparent) boilerplate about a positive
'ANA-EIA" coupled with a negative "ANA-IFA"....
It appears that the test was strictly IFA, the positive is just
reported as such, 'positive', and the 'follow-up' as a titer, not a
number near 1 as is EIA.
Quest (the lab) states that they report the pattern on all positives
with the titer as an optional follow up (which was done). Why there is
no pattern report I don't know.
This report leaves a lot to be desired, it is very confusing, for this
and other reasons not discussed here. Really poor IMHO.
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