Troponin I

TNI

TNI, Troponin I

• ORG Rapid Serum Tube

Light GREEN (PST)
Serum (Red) or Gold (SST) or Orange (OJ) or Tiger Top Serum

Preferred: Serum from an orange top, Rapid-clotting Serum specimen collection Tube (RST), which contains thrombin to help speed up the clotting process.
Alternate:   Lithium heparin plasma.   Centrifuge specimen, filter specimen, with manual sample filters (an example is SP Brand Filter Sampler Cat. P5192-3), use this filtered sample and manually front load onto the DxI or Access instrumentation.
NOTE:  Occasionally, a patient may be on anti-thrombin therapy, if there are problems with the RST tube clotting, then the specimen is to be recollected into a Lithium Heparin green top tube and processed as above for this specimen type.
Alternate: SST tubes and red top tubes also are acceptable serum specimens.  These specimens may take longer to clot, in a test where TAT is critical, these are unlikely to be the first choice to draw as specimen types.

Slight hemolysis acceptable.

 For serum, collect blood samples in RST or SST collection tubes. Allow tubes to clot adequately before centrifugation.
 
For plasma, collect blood samples in PST/Green top collection tubes.
 
The specimens must be separated from the red blood cells within 2 hours. Allow tubes to mix thoroughly before centrifugation. Keep tubes stoppered and upright at all times.
 
 Samples may still be assayed if they are stored at room temperature for up to 2 hours.
 If samples cannot be assayed within 2 hours, refrigerate samples at 2-8ºC.
If the assay cannot be completed within 24 hours, or for the storage or shipment of samples, freeze at -20ºC or colder. Samples may be stored for 6 months at -20ºC.
Samples can only be thawed once.
Samples should not be thawed in a water bath. Mix gently by inversion and centrifuge after thawing prior to samples analysis.
 

24x7

Troponin I:    Reference Range:  <0.04 ng/mL; Critical >0.20

• The 99th percentile for the DxI is < 0.03 ng/mL (with a CV that exceeds 20%). The 10% CV level is 0.04 ng/mL. ""A study using our assay (1) found that baseline and absolute delta (change in) TnI may be used in conjunction to estimate the probability of MI: 66% if baseline TnI is = 0.03 ng/mL and absolute delta TnI within 3-6 hours is = 0.01 ng/mL, vs 0.4% if baseline TnI < 0.03 ng/mL and TnI does not increase over the next 3-6 hours. High clinical suspicion but equivocal TnI results may necessitate TnI testing up to 9 hours from baseline. To maximize diagnostic accuracy, baseline TnI and delta TnI must be interpreted in relation to signs and symptoms of Acute Coronary Syndrome and clinical presentation. NOTE: In our test system the 99th percentile value (at10% CV) for a normal population is 0.04 ng/mL. (1): Storrow AB et al: Clinical Biochemistry 48 (2015) 260-267.

In myocardial infarction (MI), cTnI levels rise in the hours after the onset of cardiac symptoms, reaching a peak at 12–16 hours and can remain elevated for 4–9 days post MI. Numerous pathologies can potentially cause troponin elevations without overt ischemic heart disease. These pathologies include, but are not limited to, congestive heart failure, acute and chronic trauma, electrical cardioversion, hypertension, hypotension, arrhythmias, pulmonary embolism, severe asthma, sepsis, critical illness, myocarditis, stroke, non-cardiac surgery, extreme exercise, drug toxicity (adriamycin, 5-fluorouracil, herceptin, snake venoms), end stage renal disease, and rhabdomyolysis with cardiac injury. Importantly, these other etiologies rarely demonstrate the classic rising and falling pattern experienced with a MI which highlights the importance of serial monitoring when the clinical scenario is confusing.