When planning to switch from Abbott TDx to Roche E170 we found a shift
upwards in results, despite the fact, that serum cortisol was fully
comparable between both machines. This shift was dependent on the
extraction method and differed for each sample as well, illustrating the
huge problem of crossreactivity in immunoassays for urinary free
cortisol.
As yet, we have not switched to E170 and we are now aiming at
LC-tandemMS.
With regards,
Bart Ballieux
Dr. Ir. B.E.P.B. Ballieux
Clinical Biochemist
Leiden University Medical Centre
P.O. box 9600
2300 RC Leiden
The Netherlands
t: +3171-5262165
f: +3171-5266753
e: [log in to unmask]
-----Original Message-----
From: Clinical biochemistry discussion list
[mailto:[log in to unmask]] On Behalf Of Brian Shine
Sent: dinsdag 26 september 2006 19:23
To: [log in to unmask]
Subject: Re: Direct Urinary Cortisol using new Bayer kit
We are in a similar fix, and have not been reporting any numbers. We
were getting a bias of about 100 % on extracted urines. At present, we
are reporting any that are below 280 nmol/day as normal, any above 560
as raised, and scratching our heads about those in between (or sending
them to a lab whose results we think we can believe). In the medium
term, I guess we will look for another immunoassay, but in the long term
I think the only solution is a chromatographic method (there's a nice
report in the Annals this month).
Best wishes,
Brian Shine
> Can anybody using the new Enhanced Bayer cortisol kit for URINARY
> CORTISOL let us know how whether they are reporting patient samples
> with it. We find over recovery by about 300% against the previous kit.
> We reported this to Bayer verbally in June and sent a copy of our
comparison in July.
> Bayer were to take it up with the US, but to date no information has
> been received.
> What are the users of the previous Bayer Cortisol kit for urinary
> Cortisol doing, as the old kit is not available. We were aware with
> problems of variable recovery with the old kit. We are not using an
extraction method.
> We are in the NEQAS, and Jonathan Middle has recently sent around a
> questionnaire. The DPC and Roche methods listed are both extraction
> methods, so maybe it is naive to hope we could use a direct assay.
> However, the CVs for the three methods listed are pretty poor.
> How have other laboratories solved their problems when urinary
> Cortisol is requested?
>
> ----------------------------------------------------------------------
> --------------------
>
> Dr Helen Grimes, Dept Clinical Biochemistry, University College
> Hospital, Galway, Ireland
>
>
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