troponin-I in serum/plasma
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Indications
- assessment/diagnosis of myocardial infarction in emergency department or hospital setting
- single troponin-I levels should not be used for the diagnosis of acute myocardial infarction (a significant increase is used)
- serial samples should be drawn & tested at sequential intervals
- high-sensitivity serum troponin-I at presentation & 1 hour later suggested in protocol for rule out NSTEMI[15][16]
- for nonischemic clinical conditions, routine testing is not advised, except for cardiac prognosis in patients with chronic kidney disease & patients undergoing chemotherapy who have drug-induced cardiac injury[7]
* it seems measurement of serum creatine kinase (CK) & serum CK-MB isozymes no longer used much if at all
Reference interval
- < 0.9 ng/mL (Opus)
- < 0.5 ng/mL (Abbott AxSYM)
- < 0.2 ng/mL (DPC Immulite)
- < 0.1 ng/ml (Bayer Centaur)[9] <- MKSAP17
- < 0.04 ng/mL (Beckman Access)
- published reference intervals seem to vary widely
Principle
The Opus Troponin I is a 2 site sandwich immunoassay. The assay uses 2 goat polyclonal antibodies which recognize 2 different polypeptide segments unique to the cardiac-specific isoform of troponin-I. One of these antibodies is immobilized onto glass fiber. A 2nd antibody is conjugated to alkaline phosphatase. After washing the glass fiber, bound Troponin-I is measured by alkaline phosphatase activity using the fluorescent substrate 4-methylumbelliferyl phosphate. 3 levels of troponin-I controls are used.
Clinical significance
- elevated cardiac-specific troponin-I indicates myocardial injury due to myocardial ischemia &/or myocardial infarction[9]
- cardiac-specific troponin-I is measurable in the serum within 3 hours after onset of an acute MI[5]; earlier assays 4-6 hours
- levels < 0.05 ng/mL using high-sensitivity assay with 99.6% negative predictive value for type 1 MI on presentation or type 1 MI or cardiac death within 30 days[8]
- high-sensitivity cardiac troponin I concentration of < 5 ng/L identified those at low risk of myocardial infarction or cardiac death within 30 days[11][18]
- high-sensitivity troponin I levels normal at presentation & not increased 1 hour later can rule out MI[10]
- high-sensitivity troponin I levels elevated at presentation & not increased 1 hour later warrant inpatient observation but not coronary angiography[10]
- high sensitivity troponin I identifies more patients with acute coronary syndrome, but does not improve outcomes[14]
- peak concentrations are reached in approximately 12-18 hours after infarction
- levels may remain elevated for several days prior to returning to normal
- transient elevations in serum troponin I in hospitalized patients is associated with increased all-cause mortality & major cardiovascular complications[2]
- lower thresholds may better identify patients with acute coronary syndrome[4]
- levels < 2.5 pg/mL may identify patients with stable CAD at low risk for inducible myocardia ischemia[17]
- manufacturers' upper limit of normal for high-sensitivity cardiac troponin may be too low[19]
Increases
- myocardial injury due to myocardial ischemia &/or myocardial infarction[9]
- high-sensitivity troponin I levels elevated at presentation & not increased 1 hour later warrant inpatient observation but not coronary angiography (see troponin T cardiac in serum/plasma)
- heart failure
- asymptomatic patients with levels in the top 1/3 with higher risk for incident heart failure than those in the bottom 1/3 (RR=2.1)[13]
- sepsis
Interferences
- Improperly handled samples containing any type of particulate matter may result in falsely elevated results
- bilirubin levels > 5 mg/dL may cause falsely low values
- heterophilic antibodies.
- high intake of biotin make result in falsely low value[12]
More general terms
Additional terms
Component of
References
- ↑ Behring Diagnostics, Westwood MA (Opus procedure manual)
- ↑ 2.0 2.1 Gudmundon GS, Kahn SE, Moran JF Association of mild transient elevation of troponin I levels with increased mortality and major cardiovascular events in the general patient population Arch Lab Med & Pathology 129:474, 2005
- ↑ Clinical Guide to Laboratory Tests, 4th edition, HB Wu ed, WB Saunders, Philadelphia, 2006
- ↑ 4.0 4.1 Mills NL et al Implementation of a Sensitive Troponin I Assay and Risk of Recurrent Myocardial Infarction and Death in Patients With Suspected Acute Coronary Syndrome JAMA. 2011;305(12):1210-1216 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/21427373 <Internet> http://jama.ama-assn.org/content/305/12/1210.short
- ↑ 5.0 5.1 Keller T et al. Serial changes in highly sensitive troponin I assay and early diagnosis of myocardial infarction. JAMA 2011 Dec 28; 306:2684. PMID: https://www.ncbi.nlm.nih.gov/pubmed/22203537
- ↑ Troponin-I Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0090613.jsp
- ↑ 7.0 7.1 Newby LK et al ACCF 2012 Expert Consensus Document on Practical Clinical Considerations in the Interpretation of Troponin Elevations J Am Coll Cardiol. Nov 2012 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/23154053 <Internet> http://content.onlinejacc.org/article.aspx?articleID=1389700
- ↑ 8.0 8.1 Sadlowski C, Sadoughi S, Saitz R High-Sensitivity Cardiac Troponin Testing May Identify Low-Risk for Heart Attack. Physician's First Watch, Oct 8, 2015 David G. Fairchild, MD, MPH, Editor-in-Chief Massachusetts Medical Society http://www.jwatch.org
Shah AS, Anand A, Sandoval Y et al High-sensitivity cardiac troponin I at presentation in patients with suspected acute coronary syndrome: a cohort study. Lancet. 2015 Dec 19;386(10012):2481-8. Epub 2015 Oct 8. PMID: https://www.ncbi.nlm.nih.gov/pubmed/26454362 Free PMC Article - ↑ 9.0 9.1 9.2 9.3 Medical Knowledge Self Assessment Program (MKSAP) 17, 19. American College of Physicians, Philadelphia 2015, 2023
- ↑ 10.0 10.1 10.2 Neumann JT et al Diagnosis of Myocardial Infarction Using a High-Sensitivity Troponin I 1-Hour Algorithm. JAMA Cardiol. Jul 1;1(4):397-404, Published online June 01, 2016 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/27438315 <Internet> http://cardiology.jamanetwork.com/article.aspx?articleid=2526373
Carlton E et al Evaluation of High-Sensitivity Cardiac Troponin I Levels in Patients With Suspected Acute Coronary Syndrome. JAMA Cardiol. Jul 1;1(4):405-12, Published online June 01, 2016 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/27438316 <Internet> http://cardiology.jamanetwork.com/article.aspx?articleid=2526374
Morrow DA Evidence-Based Algorithms Using High-Sensitivity Cardiac Troponin in the Emergency Department. JAMA Cardiol. Jul 1;1(4):379-81, Published online June 01, 2016 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/27438311 <Internet> http://cardiology.jamanetwork.com/article.aspx?articleid=2526371 - ↑ 11.0 11.1 Chapman AR, Lee KK, McAllister DA et al Association of High-Sensitivity Cardiac Troponin I Concentration With Cardiac Outcomes in Patients With Suspected Acute Coronary Syndrome. JAMA. Published online November 11, 2017 PMID: https://www.ncbi.nlm.nih.gov/pubmed/29127948 https://jamanetwork.com/journals/jama/fullarticle/2662908
Shah AS, Anand A, Sandoval Y et al High-sensitivity cardiac troponin I at presentation in patients with suspected acute coronary syndrome: a cohort study. Lancet. 2015 Dec 19;386(10012):2481-8. Epub 2015 Oct 8. PMID: https://www.ncbi.nlm.nih.gov/pubmed/26454362 Free PMC Article - ↑ 12.0 12.1 FDA MedWatch Nov 28, 2017 Biotin (Vitamin B7): Safety Communication - May Interfere with Lab Tests. https://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm586641.htm
FDA Safety Communcation. Nov 5, 2019
UPDATE: The FDA Warns that Biotin May Interfere with Lab Tests: https://www.fda.gov/medical-devices/safety-communications/update-fda-warns-biotin-may-interfere-lab-tests-fda-safety-communication
Biotin Interference with Troponin Lab Tests - Assays Subject to Biotin Interference. https://www.fda.gov/medical-devices/vitro-diagnostics/biotin-interference-troponin-lab-tests-assays-subject-biotin-interference - ↑ 13.0 13.1 Evans JDW, Dobbin SJH, Pettit SJ et al High-Sensitivity Cardiac Troponin and New-Onset Heart Failure. A Systematic Review and Meta-Analysis of 67,063 Patients With 4,165 Incident Heart Failure Events. JACC: Heart Failure. January 2018 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/29331272 <Internet> http://heartfailure.onlinejacc.org/content/early/2018/01/02/j.jchf.2017.11.003
Jaffe AS, Miller WL. Meta-Analyses and Interpretation of Troponin Values in Heart Failure. JACC: Heart Failure. January 2018 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/29331273 <Internet> http://heartfailure.onlinejacc.org/content/early/2018/01/02/j.jchf.2017.12.001 - ↑ 14.0 14.1 Shah ASV, Anand A, Strachan FE et al. High-sensitivity troponin in the evaluation of patients with suspected acute coronary syndrome: A stepped-wedge, cluster- randomised controlled trial. Lancet 2018 Aug 28; PMID: https://www.ncbi.nlm.nih.gov/pubmed/30170853 Free Article https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(18)31923-8/fulltext
- ↑ 15.0 15.1 Reichlin T, Twerenbold R, Wildi K et al Prospective validation of a 1-hour algorithm to rule-out and rule-in acute myocardial infarction using a high-sensitivity cardiac troponin T assay. CMAJ. 2015 May 19;187(8):E243-52 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/25869867 Free PMC Article <Internet> http://www.cmaj.ca/content/early/2015/04/13/cmaj.141349.full.pdf
- ↑ 16.0 16.1 Twerenbold R, Neumann JT, Sorensen NA Prospective Validation of the 0/1-h Algorithm for Early Diagnosis of Myocardial Infarction. J Am Coll Cardiol. 2018 Aug 7;72(6):620-632. PMID: https://www.ncbi.nlm.nih.gov/pubmed/30071991
- ↑ 17.0 17.1 Hammadah M, Kim JH, Tahhan AS et al Use of High-Sensitivity Cardiac Troponin for the Exclusion of Inducible Myocardial Ischemia: A Cohort Study. Ann Intern Med. 2018. Nov 6. <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/30398528 <Internet> http://annals.org/aim/article-abstract/2712482/use-high-sensitivity-cardiac-troponin-exclusion-inducible-myocardial-ischemia-cohort
Devereaux PJ The Potential for Troponin to Inform Prognosis in Patients With Stable Coronary Artery Disease. Ann Intern Med. 2018. Nov 6 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/30398543 <Internet> http://annals.org/aim/article-abstract/2712931/potential-troponin-inform-prognosis-patients-stable-coronary-artery-disease - ↑ 18.0 18.1 Januzzi JL Jr, Suchindran S, Hoffmann U et al. Single-molecule hsTnI and short-term risk in stable patients with chest pain. J Am Coll Cardiol 2019 Jan 29; 73:251. PMID: https://www.ncbi.nlm.nih.gov/pubmed/30678753 https://www.sciencedirect.com/science/article/pii/S073510971839199X
Collinson P. Troponin in suspected coronary artery disease: Headed toward a new paradigm in cardiac biomarkers? J Am Coll Cardiol 2019 Jan 29; 73:261. PMID: https://www.ncbi.nlm.nih.gov/pubmed/30678754 https://www.sciencedirect.com/science/article/pii/S0735109718392611 - ↑ 19.0 19.1 Mariathas M, Allan R, Ramamoorth S et al True 99th centile of high sensitivity cardiac troponin for hospital patients: prospective, observational cohort study. BMJ 2019;364:l729 PMID: https://www.ncbi.nlm.nih.gov/pubmed/30867154 Free Article https://www.bmj.com/content/364/bmj.l729