 |
 |
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 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%