Mike,
Many answers:
Clinical: A single presentation cTnT of 17 does not tells us much other than that there is a degree of cardiac damage. It does not tell us whether it is acute. A second cTnT level of 17 shortly after (not sure what the time difference is in your patient, but would need to be greater than 3 hours) would indicate chronic cardiac damage and causative factors need to be investigated such as renal failure etc. (and three full slides of causes!). what was the op and how informative are troponins in the hours after operation?
Technical 1: I agree with Graham, cTnT and cTnI measure different things at the low end and could cause a bit of head scratching, but I would believe the more sensitive assay.
Technical 2: I have not (consciously) seen heterophile antibody interference with troponin assays, but they may be out there evading the assay's defence shields. As all cTnT assays are the same, then any interference would be the same across analysers.
Technical 3: how old was the patient?
If it were my result: Not an acute event, but would conclude that something cardiac was going on. Would like a check up to see whether I had one of the numerous causes of chronic elevation in cTnT or just post op troponinitis.
martin
-----Original Message-----
From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of Graham jones
Sent: 21 May 2013 21:10
To: [log in to unmask]
Subject: Re: Troponin
Michael,
This is the pointy end of the different assays.
Any method comparison (especially TnT and TnI) which measure similar but not identical molecules will do this. Any TnT v TnI comparison shows the scatter near the decision point. I recall meeting with our cardiologists when considering a change from Centaur TnI ultra to 4th gen TnT. I said the sensitvity and specificity were the same (sighs of relief), but some of the patients you sent home last week you would now keep, and some of the patient's you kept in last week you would now discharge (not so happy).
I would belive the more sensitive assay.
Regards,
Graham
>>> "Colley, Michael" <[log in to unmask]> 05/22/13 2:10 AM >>>
A post-op patient at the local private hospital had a twinge of pain, so a Troponin T was performed by TDL (who do the Path for them). The value of 17 was obtained (ULN 14) so he was sent to Great Western as a potential cardiac patient.
A further sample was analysed at GWH and the Trop I was 20 (ULN 40 ) so he was, eventually discharged.
In an attempt to clarify, the GWH sample was send to TDL, who analysed it for TropT – again getting 17 (on two different analysers) and for Trop I – again getting 20.
So the question is "has the patient got myocardial damage?" as per Trop T or hasn't he as per Trop I.
Michael
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