In message <[log in to unmask]>, Jonathan Kay
<[log in to unmask]> writes
>
> Department of Clinical
>Biochemistry, Oxford Radcliffe Hospitals
>
>
>
> Biochemical markers of
>myocardial damage: Change of policy
>
>31 August 2000
>
>
>
>On 5 September 2000 we will change the biochemical markers offered to detect
>myocardial damage. This affects all Oxford hospitals and general practitioners
>who use the Oxford laboratory. It does not affect the Horton Hospital
>or general practitioners who use the Banbury laboratory.
>
>The major marker will be cardiac Troponin I. This has much greater predictive
>power than the current battery of tests used. The concentration is increased in
>nearly all patients with myocardial infarction after 12 hours, and
>remains elevated for more than 5 days.
>
>For suspected myocardial damage one specimen should be sent when the patient is
>first seen, and a second at 12 hours after the onset of symptoms. The 12 hour
>specimen should always be collected. The time after onset of
>symptoms must be written on the request card.
>
>If a second infarction is suspected the protocol should start again with an
>immediate specimen and one 12 hours after the suspected new event.
>
>The reference interval for serum cardiac Troponin I in the healthy population
>is about 0 to 0.2 ng/mL.
>
>After the diagnosis of myocardial infarction or other acute coronary syndrome,
>assay of AST, CK, LD or CRP adds no value and should not be requested unless
>otherwise clinically indicated.
>
>The assays will be run three times every day (0900 and 1500 seven days a week,
>and 2100, Monday to Friday and 2200, Saturday and Sunday). It will not be
>possible to run single or urgent requests for Troponin in
>addition to these three batches.
>
>The required specimen is serum, and the preferred container is a Vacutainer SST
>(which has a yellow cap). This should be sent in addition to the plasma
>specimen used for assays such as potassium, creatinine, cholesterol
>and triglycerides.
>
>Please contact me with any queries about this policy, and the Duty Biochemist
>(JR bleep 1718) for help in selecting investigations or interpreting reports.
>
>
>Notes
>
>
>1 The assay method used is the DPC system on the Immulite 1 analyser. Different
>methods give different results and it is not safe to interpret results produced
>with one method with guidelines based on different method.
>
>2 As soon as the Troponin assay is in robust clinical use we will discontinue
>the assay of CK-MB.
>
>3 Requests for "cardiac enzyme" or similar with a plasma specimen but no serum
>specimen will get CK (not CK-MB, not AST, not LD, not Troponin).
>
>4 The outcome of this change will be audited and it is likely that the policy
>will change when the results of the audit are known.
>
>5 The background to the choice of markers of myocardial damage is available on
>the Oxford Clinical Intranet at: http://193.39.3.13/labmed/hbk/HOME001.HTM
>
>
>Dr Jonathan Kay
>
>Consultant Chemical Pathologist
>
>JR ext 20470
>
>
>
>"Mainwaring-Burton Richard (RGZ)" wrote:
>
>> > Can I start a conversation regarding the 'dwell-time' between chest pain
>> > and measurement of Troponin T +/or I ?
>> > I am very concerned that some people are using 6 hrs and others (like me)
>> > are using 12.
>> >
>> > My feeling to start the discussion is that when using Troponins as a MI
>> > excludogram, 12 hrs should be used, and that this is the most economic
>> > usage of the assay, but a 6 hr assay may give too many potentially
>> > litigenous/dangerous false negatives.
>> >
>> > Single assay confirmation of MI for those who can afford it may well be OK
>> > before 12 hrs, depending on the size of infarct. I can see the attraction
>> > of earlier tests in case Troponin is being used as a thrombolysis
>> > indicator, which necessitates treatment within 12 hours.
>> >
>> > Horrors - the bandolier article looks as if 'they' will want [admission],
>> > [3hr] and [12hr] to diagnose MI. Has anyone succeded in convincing their
>> > trust to transfer adequate funding from Medicine/A&E to Laboratory budgets
>> > ?
>> > <http://www.jr2.ox.ac.uk/bandolier/band93/b93-5.html>
>> >
>> > I don't think the NSF on hearts is explicit enough.
>> > With best wishes
>> >
>> > Richard
>> >
>> >
>
>[ A MIME text / x-vcard part was included here. ]
>
On No the 12 hour from symptoms myth persists
The NACB document said - and I fully support it - that time from admission is
essential
The only (nearly) 100% certainty is a troponin sample 12 h from ADMISSION
--
Paul Collinson
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