Troponin-I High Sensitivity - Range & Mesaba Clinics, Northland, Southdale, UMMC/UMMCH West


Abbrev Code:TNIH   
Order Code:LAB747Order Name:Troponin I
Synonyms:Cardiac Enzyme
Methodology:Chemiluminescence
CPT Codes: 84484 x1
Turnaround Time:Performed and reported 24 hours/day.
Associated Links:

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Collection Instructions

Specimen:Blood
Optimal Volume:2.5 mL
Minimum\Peds Volume:0.6 mL
Collection Instructions:Chemistry Tests Containers Chart
Serial sampling is recommended to detect temporal rise and fall of cTnl levels characteristic of AMI.
Contraindications:Large doses of biotin (10 mg or more per day) may cause clinically significant interference in troponin levels. If interference is suspected, it is strongly recommended that biotin is discontinued for at least one week prior to retesting.


Processing and Shipping

Specimen Processing:Centrifuge and aliquot 1.25 mL, 0.2 mL minimum. Store in refrigerator.
Shipping Instructions:Ship at refrigerated temperature to arrive within 24 hours. Alternatively, ship on dry ice.
Fairview Clinics: Ship samples to arrive the same day.
Stability:8 hours at room temperature; 24 hours refrigerated temperature; 40 days at -20°C, or 1 year at -70°C. Do not store in frost-free freezer; freeze only once and mix thoroughly after thawing. Centrifuge frozen samples for 10 m at 2200 x g before analysis.
Test Performed at or Referral Lab Chemistry  (Northland, Oxboro Clinic, Range, Range Clinics, Southdale, UMMC/UMMCH-West Bank)


Interpretive

Critical Range:Greater than or equal to 120 ng/L (all ages)
Reference Range:99th percentile cutoffs:
Female (all ages): <54 ng/L
Males (all ages): <79 ng/L
MHVF High Sensitivity Troponin I Pathway
 
Limitations:Interpretation of cTnl results should be done only in the context of the overall clinical picture, e.g., clinical history, ECG, and other laboratory tests indicative of cardiac damage. The triage of patients with chest pain should be based on serial samples and the typical rise and fall pattern of cTnl characteristic of cardiac damage. 
Use:The International Federation for Clinical Chemistry and Lab Medicine (IFCC) standard, defines "high sensitivity" cardiac troponin assay as the ability to detect troponin I concentrations precisely with a coefficient of variation, <10 at or below the 99th percentile URL and measurable in >50% of normal healthy individuals. Compared to contemporary troponin I assays, high sensitivity troponin I assays can detect lower levels of troponin I with improved precision and more reliable changes in ta patient's troponin levels to aid in timely diagnosis of AMI.

Clinically validated rule-in/out algorithms specific for high sensitivity assay can help achieve high sensitivity and specificity for the detection of acute MI at presentation and shorten the time interval to the second cardiac troponin. These might substantially reduce the delay to diagnosis, translating into shorter stays in the emergency department and lower costs.

In contemporary assays, values are reported in μg/L and high sensitivity cardiac troponin (hs-cTn) assays are reported in ng/L. If the concentration is substantially elevated, e.g. above 100 ng/L, both assays provide identical information. However, in contrast, only hs-cTn allows a precise differentiation between "normal" and mildly elevated concentrations, thus detects a relevant proportion of patients missed with the conventional assay who have hs-cTn concentrations above the 99th percentile possibly related to AMI. The limit of detection varies among the differnt hs-cTn assays between 1 ng/L and 5 ng/L and the 99th percentile varies among the different hs-cTn assays, mainly being between 10 ng/L and 20 ng/L.   Vishakantha Murthy, PhD, MBA, CCRP and Danni Li, PhD, DABCC, FACB


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