The two test approach seems to be an acceptable practice:
Example, TSH and/or followed by a free hormone test (if necessary).
The efficiency and cost-effectiveness of the two test approach are
significantly improved when a system (LIS + Random Access Automated
Analyser + Bar Code Technology) which allows for reflex testing is
employed. The need to save and/or retrieve specimens for the follow-up
tests is greatly reduced.
David Acheampong-Mensah
Clinical Biochemist
LabMed Consulting Inc.
Toronto, Ontario, Canada.
[log in to unmask]
>
>
>Paul Collinson writes
>
><<ow here is something that will ignite controversy
>Is there is =93best buy=94 for TFT=92s
>
>My endocrinologist is quoting at me the guidelines published by the
>British endocrine society/RCP and considers that two tests should be
>done on all patients.
>
>His view is TSH plus fT3
>
>I read these as saying that diagnosis should be conformed by a free
>hormone e.g. TSH then fT3 or fT4 if the TSH is not =93normal=94.
>
>Questions
>
>Does everybody measure 2?
>
>Has anyone audited what is the best policy ( I mean real audit, not a
>survey)?
>
>Is there any outcome data?
>
>What is published?=20
>
>
>--=20
>Paul Collinson>>
>>>>>>>
>
>
>
>I agree with your endocrinologist.
>TFTS are done in a number of contexts and on samples
>drawn from different populations - I work closely
>with an endocrinologist who has a large hypopit workload.
>Thus generalisations are dangerous and the figure of 3% from
>Australia although helpful is not applicable everywhere.
>
>We did a study using an agreed algorithm and simulated doing
>TSH as a front line test. We found that we had to do a second line
>test on around 60% of samples. By the time you had allowed for the
>cost of finding samples twice and all the general thrashing around
>involved we were deeply unimpressed with the reagent savings.
>Two tests do not cost twice as much as one - the difference is much
>smaller. (We ended up with a situation that was broadly cost neutral
because we
>negotiated a larger reagent discount!). We also were struggling to
provide
>an appropriate turnaround time ( and delaying the most abnormal results
>the most!).
>
>I accept that TSH alone is adequate in managing patients on thyroxine
>replacement. However I manage 850 such patients and the combination of
results
>(total T4 and TSH) are often informative even in that group (
suggesting things
>like
>non compliance or non-thyroidal illness).
>
>American endocrine organisations have come out strongly in favour of
>two tests and I absolutely agree with them especially for diagnostic
tests
>(ie the first time around).
>
>Sites that only do TSH simply do not know how many diagnoses they miss
>(including TSH omas and other rarieties) and whilst the numbers may be
small
>these treatable conditions will certainly be missed by the lab.
>
>Two tests also act as form of internal QA and we cetainly get
clinically
>implausable
>results that turn out to be lab errors on repeat (short samples or
whatever).
>In some cases
>initially normal TSHs turn out to be wrong. Blunder rates may run in
most
>labs at between 0.01% and 0.1% or higher (historically a figure of 1%
has been
>found).
>
>My endocrinologist and I agree that we would not like to start life
long
>therapy on the basis of one test done in singlicate. For that reason it
appears
>more useful to do a TSH and Total T4 in singlicate rather than a TSH in
>duplicate.
>
>There is a difficult tradeoff here between an obvious and "easy" cost
save
>and a quality improvement that is real but hard to price.
>
>Maybe there is no "right" answer, just a judgement that should be made
in the
>light
>of the population served and in close local discussion with the
relevant
>clinicians.
>Certainly very large studies in many different settings would have to
be made to
>establish
>the answer and as innovation ensures that tests should get cheaper over
time it
>may
>become increasingly unimportant.
>
>More interesing questions (to my mind) include strategies to eliminate
>worthless repeat tests
>done within days or weeks of each other (often one by a GP and one by
the
>hospital) and
>trying to eliminate situations where thyroid function has not been for
far too
>long
>in the course of a illness resulting in delayed diagnosis.
>
>
>James Falconer Smith.
>
>
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