Dear Martin,
 
That is why we add this cautionary comment after the cut off levels:
 

Always interpret TnI results within the clinical context and ECG findings.

Above comments apply to samples taken 12h post-event.

 

The cut off for any troponin method is derived by the manufacturer. For Siemens tropnin I ultra, 112 patient with classical features of MI fulfilling WHO criteria had their TnI measured and they arrived at a cut off of 0.78 ug/L. This WHO defined cut off reflects a higher myocardial damage compared to the ESC/ACC recommendation. Therefore a diagnosis of AMI can still be entertained at levels below 0.78 depending on clinical scenario and ECG findings especially NSTEMI. The comment for TnI 0.04 – 0.78  ug/L suggests myocardial damage consistent with ACS and/or NSTEMI.

 

regards

 

Mohammad

 


From: Myers Martin (LTHTR) <[log in to unmask]>
To: [log in to unmask]
Sent: Wednesday, 3 December, 2008 10:08:25
Subject: Re: Troponins reporting

I am a little uneasy about the "AMI Cut offs" that would indicate AMI.   Are these evidence based?  What does an arbitary cut off, e.g. 0.1 for troponin T (at a fixed time point of 12 hr), actually mean and how would one interpret the following:
admission TnT = <0.01
12 hour troponin T = 0.09
 
The Expert Consensus Document, Universal Definition of Myocardial Infarction, Circulation 2007;116;2634-2653;  defines a acute myocardial infarction as (amongst others) : a rise and/or fall in [troponin] with at least one level above the 99th percentile of the URL together with evidence of myocardial ischaemia (at least one of the following: symptoms, ECG changes, pathological Q wave, imaging evidence).  There is not mention of another arbitary cut-off which would indicate AMI. 
 
martin
 
 
-----Original Message-----
From: Clinical biochemistry discussion list [mailto:[log in to unmask]]On Behalf Of Indovina, Joe [OCDUS]
Sent: 02 December 2008 18:39
To: [log in to unmask]
Subject: Re: Troponins reporting

Good discussion

 

To help I went through my files and put together a table of different vendors troponin assay cut offs and 99% URL

 

I used the package insert sheets that I have and thus urge caution as some may not be 100% current

 

What it does show is, in my opinion, the importance of identifying on the lab report as Mohammad does

 

Abbott AxSYM TnI ADV

Abbott AxSYM TnI ADV

Beckman AccuTnI

Bayer Centaur Ultra TnI

Dade RXL

DPD STAT TnI

Roche TnT

Vitros Trop I ES

 

 

 

 

 

 

 

 

 

 

 

AMI Cut-off

0.4

0.3

0.5

0.8

1.5

??

0.1

0.120

 

 

 

 

 

 

 

 

 

 

 

URL 99th Percentile

<= 0.04

0.012

<= 0.04

0.04

<= 0.05

0.2

0.01

0.034

 

 

 

 

 

 

 

 

 

 

 

units

ng/mL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

-----Original Message-----
From: Clinical biochemistry discussion list [mailto:[log in to unmask]]On Behalf Of Mohammad Al-Jubouri
Sent: Tuesday, December 02, 2008 9:06 AM
To: [log in to unmask]
Subject: Troponins reporting

 

There are various cut offs used for TnT and TnI reporting. The following aucomms are added to our TnI reports (Advia Centaur TnI ultra assay) using the manufacturer's recommendations:

 

< 0.05 ug/L           No obvious myocardial damage.

 

0.05 – 0.78 ug/L   Myocardial damage consistent with acute coronary syndrome and/or NSTEMI

 

> 0.78 ug/L          Myocardial damage consistent with acute MI (WHO criteria)

 

Always interpret TnI results within the clinical context and ECG findings.

Above comments apply to samples taken 12h post-event.

 

All these comments are designed to enlighten the user about how to interpret the TnI test result, however it seems that a lot of patients with positive TnI results are labelled as acute MI despite the absence of other criteria to diagnose myocardial ischaemia.

 

How do other people report their Troponin results?

Is there a better way of reporting lab tests using test's sensitivity/specificity and positive/negative predictive values, rather than just reporting a numerical result with a reference range of dubious origin?

 

Many thanks

 

Mohammad

 

 

From: Mohammad Al-Jubouri <[log in to unmask]>
To: [log in to unmask]
Sent: Monday, 1 December, 2008 15:54:04
Subject: Re: Troponin I - quoted cut-off value 0.10 ug/L

Richard,

 

We actually use 0.05 ug/L as the cut off for detecting myocardial damage (not classical MI cut off) on the Advia Centaur TnI ultra assay. As myocardial damage can be of varying aetiology ischaemic & non-ischaemic, we leave it to the clinicians to decide if the myocardial damage is due to acute coronary ischaemia or due to some other causes.

 

David's original statement is probably related to a recent NEQAS interpretative comment.

 

Best wishes

 

Mohammad
 

 

 

From: Mainwaring-Burton Richard (RGZ) <[log in to unmask]>
To: [log in to unmask]
Sent: Monday, 1 December, 2008 15:34:36
Subject: Re: Troponin I - quoted cut-off value 0.10 ug/L

THAT IS WRONG !!!

0.1   is the M.I. cutoff for TnT and NOT TnI !

 

I suspect that the 0.1 value may be the lowest claimed detectable for TnI

 

Read ALL the small print, not just the box.

 

I never trust what it says on the box : I keep seeing "Open Other End " - and it never is !

with best wishes
Richard
Richard Mainwaring-Burton
Consultant Biochemist
Queen Mary's Hospital
Sidcup, Kent
020-8308-3084

-----Original Message-----
From: Mohammad Al-Jubouri [mailto:[log in to unmask]]
Sent: 01 December 2008 15:05
To: [log in to unmask]
Subject: Re: Troponin I - quoted cut-off value 0.10 ug/L

 

I interpret it as any TnI value of 0.1 ug/L and above indicates myocardial damage, and any value < 0.1 ug/L does not indicate myocardial damage.

 

regards

 

Mohammad 
 

Dr. M A Al-Jubouri, MB ChB, MSc, FRCP Edin, FRCPath
Consultant Chemical Pathologist

 

 

From: David Burgess <[log in to unmask]>
To: [log in to unmask]
Sent: Monday, 1 December, 2008 14:58:32
Subject: Troponin I - quoted cut-off value 0.10 ug/L

Please - how do you interpret the phrase, "Troponin I was analysed on an
Advia Centaur: quoted cut-off value 0.10 ug/L"
Regards, David.

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------ACB discussion List Information-------- This is an open discussion list for the academic and clinical community working in clinical biochemistry. Please note, archived messages are public and can be viewed via the internet. Views expressed are those of the individual and they are responsible for all message content. ACB Web Site http://www.acb.org.uk List Archives http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html List Instructions (How to leave etc.) http://www.jiscmail.ac.uk/

 

------ACB discussion List Information-------- This is an open discussion list for the academic and clinical community working in clinical biochemistry. Please note, archived messages are public and can be viewed via the internet. Views expressed are those of the individual and they are responsible for all message content. ACB Web Site http://www.acb.org.uk List Archives http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html List Instructions (How to leave etc.) http://www.jiscmail.ac.uk/

------ACB discussion List Information-------- This is an open discussion list for the academic and clinical community working in clinical biochemistry. Please note, archived messages are public and can be viewed via the internet. Views expressed are those of the individual and they are responsible for all message content. ACB Web Site http://www.acb.org.uk List Archives http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html List Instructions (How to leave etc.) http://www.jiscmail.ac.uk/