We can not be falsely reassured that any of our
results is interpreted alongside the clinical findings
especially when the clinical scenario is blurred and
has a great subjective element to its interpretation.
The physician's intra and inter-individual variations
in assessing the history of chest pain and ECG
findings are not acceptable by any of our QC
parameters. The objectivity of cardiac troponins, when
we get them right, far exceeds the clinical acumen of
some physicians.
--- Ian Barlow <[log in to unmask]>
wrote: > We also use a single (at least 12 hrs post
chest
> pain) Trop I run in
> Immuno-1 to help diagnose ACS and have not had any
> false positive or
> negatives (as far as we are aware) neither have we
> detected any
> interferences from heterophilic antibodies.
> I accept that in an ideal world we would do serial
> Trops rather than a
> single one but costs would then become a major
> issue. But lets not forget
> that all results must be interpreted alongside the
> clinical situation.
> - Ian
>
> > -----Original Message-----
> > From: Mohammad Al-Jubouri
> [SMTP:[log in to unmask]]
> > Sent: Thursday, June 22, 2000 12:34 PM
> > To: Grimes, Helen;
> [log in to unmask]
> > Subject: RE: Appropriate timing for TnI
> >
> > The issue of interfering antibodies with TnI
> > immunoassay is very important. As far as I am
> aware
> > there is no data defining the extent of the
> problem
> > with TnT or TnI immunoassays. We have been using
> Bayer
> > Immuno 1 TnI assay in conjunction with classical
> > enzymes for a year now, we did not come across a
> > single false positive result. However we did have
> a
> > false negative result once or twice due to small
> > sample volume and semiclotted sample. I agree that
> a
> > single TnI per one episode of chest pain may not
> be
> > ideal.
> >
> > Regards.
> >
> > --- "Grimes, Helen" <[log in to unmask]> wrote: >
> > Further to the discussion on appropriate timing
> for
> > > Troponin I, I would have
> > > thought it unwise to interpret a single Troponin
> I
> > > level, as we find a
> > > significant number of patients with interfering
> > > autoantibodies for Troponin
> > > I on the Beckman Access, and we pick them up
> when 2
> > > samples show the same
> > > level of Troponin I but without a change in
> > > myoglobin and CPK. Not all
> > > samples with no change will have such
> antibodies,
> > > there would appear to be
> > > other interferants.
> > > Helen Grimes
> > > Dept of Clin Biochem,
> > > Univ Coll Hosp Galway
> > >
> > > -----Original Message-----
> > > From: Peter Auld
> [mailto:[log in to unmask]]
> > > Sent: None
> > > To: [log in to unmask];
> > > [log in to unmask]
> > > Subject: Re: Appropriate timing for TnI
> > >
> > > Hi
> > >
> > > re: Timing of cTnI sampling.
> > >
> > > Our email has been on the blink so
> apologies
> > > for not
> > > sending this
> > > reply sooner. We have some data from our
> work
> > > with the
> > > Abbott AxSYM
> > > cTnI assay which may be of interest. We
> > > looked at the
> > > kinetics of
> > > patients with ?ACS (n@). Of those with a
> > > diagnosis of
> > > ACS (n%) the
> > > mean (SE) doubling time was 2.2 (0.3)h,
> the
> > > time to
> > > peak was 17.5
> > > (1.6)h from the onset of max chest pain
> and
> > > the
> > > elimination half-life
> > > was 23.3(1.3)h. The clinical sensitivity
> at
> > > up to 5h,
> > > up to 6h and up
> > > to 12h post onset of max chest pain was
> 32,
> > > 68 and 100%
> > > respectively.
> > >
> > > Also in a separate study we estimated the
> > > sensitivity
> > > of cTnI for AMI
> > > (cutoff 2 ug/L) on admission
> (presentation)
> > > at 50.5%
> > > and 12h post pain
> > > onset at 97.7% (n91).
> > >
> > > Our routine protocol is now a single 12h
> cTnI
> > > - we
> > > dropped cardiac
> > > enzymes after a three month review due to
> > > lack of
> > > interest!
> > >
> > > Peter W Auld
> > > Dept Clin Biochem
> > >
> > > Antrim Hospital
> > >
> > > ______________________________ Reply Separator
> > > _________________________________
> > > Subject: Appropriate timing for TnI
> > > Author: [log in to unmask] at XINTERNET
> > > Date: 6/6/00 8:31 AM
> > >
> > >
> > > Dear all
> > > I would welcome your views on timing of
> samples
> > > for a
> > > single TnI measurement for the assessment of
> acute
> > > coronary syndrome. Most laboratories have
> adopted
> > > 12 h
> > > post admission whether they measure TnI or
> TnT. If
> > > we
> > > are aiming at measuring peak troponin levels,
> > > which
> > > correlate better with infarct size and
> prognosis,
> > > then
> > > this timing may not always hit the peak level.
> > > From my
> > > limited experience of measuring TnI in acute
> MI
> > > patients admitted to our CCU, it is usually
> > > cardiac
> > > enzyme 2 or 3 which show the peak TnI level
> > > coinciding
> > > with peak CK levels (NB: in our Hospital CCU,
> CK
> > > and
> > > AST are measured at 8hrly intervals).
> Therefore
> > > 16-18
> > > hours post admission timing may be more
> > > appropriate in
> > > this regard. Alternatively, we should probably
> aim
> > > at
> > > getting two troponin results taken 8 hours
> apart,
> > > which will give us a slope from which we can
> > > estimate
> > > infarct size. Also having a second sample for
> > > troponin
> > > will provide a saftey net should any thing
> goes
> > > wrong
> > > analytically or otherwise with the first
> sample.
> > > The
> > > cost of course will double. Your expert
> opinion on
> > > this matter is greatly appreciated.
> > >
> > > ÿÿ
> > > Dr. M A Al-Jubouri
> > > Consultant Chemical Pathologist
> > > Whiston Hospital
> > > Prescot
> > > Merseyside L35 5DR
> > > UK
> > >
> > >
> __________________________________________________
> > > Do You Yahoo!?
> > > Yahoo! Photos -- now, 100 FREE prints!
>
=== message truncated ===
=====
Dr. M A Al-Jubouri
Consultant Chemical Pathologist
Whiston Hospital
Prescot
Merseyside L35 5DR
UK
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