Marc:
Would you please provide more information about the manufacturer of the serum filter system?
Is this a filter that is manually pushed down from the top of specimen tubes? Do you do this with all specimens or just troponin specimens?
regards, Andrew
Dr. A. Lyon, Univ. Calgary & Calgary Lab Services.
----- Original Message -----
From: "Dellerba, Marc" <[log in to unmask]>
Date: Thursday, October 26, 2006 2:21 am
Subject: Re: False high Trop T
> We successfully used a "serum filter system" on Trop I samples
> (LiHep) with
> micro-clots, I assumed on these results the clots formed before
> analysis?
> Marc Dellerba
> Victoria Hospital. Blackpool.
>
>
> -----Original Message-----
> From: Richard Stott [[log in to unmask]]
> Sent: 25 October 2006 21:16
> To: [log in to unmask]
> Subject: Re: False high Trop T
>
>
>
> Elizabeth suggested I should send my proposed mechanism for false
> positivesto the list.
>
> Our experience was based on serum samples which clotted in the
> analyser cups
> of the 1010 so I know clots can form during the assay in the old kit
> formulation. Here is the suggestion which I sent her -
>
> << Now that we know it is an EDTA sample we also know that there is
> potential for the anticoagulation of the sample to be reversible.
> If there
> is insufficient dissolved EDTA in the sample (especially with a
> poorly mixed
> ED sample transported to the lab quickly?) you just need a little
> calciumfrom the assay buffer and the plasma might be able to clot
> again.
> Now try to visualise a micro clot forming during the assay
> incubation. It
> would include the magnetic particle solid phase and some of the
> labelledantibody trapped within the pourous clot.
>
> Once the incubation is over, the reaction mixture enters the magnetic
> seperation chamber. Tthe electromagnet comes on and pulls all of the
> magnetic particles to the side. Because the clot contains magnetic
> solidphase it is attracted too. The wash fluid removes all unbound
> tracer from
> the liquid phase but cannot remove the tracer within the clot
> because there
> is not enough time for it to diffuse out (high molecular weight!).
>
> Now we displace the metal ions (including those within the clot -low
> molecular weight reagents which can diffuse finto the clot relatively
> rapidly!) and perform the electroluminescent determination -
> Signal is
> produced because there is tracer present, so you measured some
> troponin!>>
>
>
>
> Regards
>
> Richard Stott PhD
> Dept. Clinical Biochemistry, Doncaster Royal Infirmary.
> Doncaster, UK
>
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