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.
>
>


______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%