Introduction

Accurate diagnosis of cardiac emergencies is a critical responsibility of emergency physicians. The extensive differential diagnosis of chest pain must be narrowed rapidly and accurately to enable timely, lifesaving interventions.[1] In addition to the history and physical examination, several diagnostic modalities assist in distinguishing among potential causes of chest pain.[2] Measurement of cardiac troponins (cTns) has become an integral component of cardiac evaluation and diagnosis.[3]

CTns were introduced for clinical application in 1995 following the approval of the first cTn T (cTnT) assay.[4] Subsequent advances in assay design demonstrated that enhanced cardiac specificity and markedly improved sensitivity increased the diagnostic accuracy and frequency of cardiovascular disease detection, particularly with the development of high-sensitivity cardiac troponin (hs-cTn) assays.[5]

Progressive refinement of troponin assays has significantly improved the speed and precision of acute myocardial infarction (AMI) detection. Fourth-generation assays identified substantial myocardial injury but exhibited limited early sensitivity. High-sensitivity 5th-generation assays enabled the detection of minute troponin concentrations at single-digit nanogram-per-liter levels, facilitating earlier diagnosis and enabling accelerated rule-out protocols. However, increased analytical sensitivity resulted in measurable elevations in nonischemic conditions such as chronic kidney disease (CKD) and heart failure. Sixth-generation assays demonstrate further improvements in analytical precision and reproducibility, enhancing differentiation between acute ischemia and other etiologies of troponin elevation and optimizing timely clinical decision-making in emergency care.

Etiology and Epidemiology

Troponin exists in 3 distinct molecular isoforms corresponding to fast-twitch skeletal muscle, slow-twitch skeletal muscle, and cardiac tissue.[6] The skeletal isoforms are comparable in molecular mass (approximately 20,000 Da) and exhibit amino acid sequence heterogeneity of roughly 40%.[7] The cardiac isoform also exhibits approximately 40% sequence heterogeneity relative to the skeletal isoforms and contains an additional 31 residues at the amino terminus, allowing immunologic differentiation between cardiac and skeletal troponins.[8]

Within the myocyte, troponins may be bound to the contractile apparatus or remain free in the cytosol, comprising approximately 6% to 8% of total content for cTnT and 3.5% for cTnI.[9] CTnT and cTnI differ in amino acid composition and may be distinguished immunologically.[10] Immunoassays targeting cardiac-specific troponin isoforms detect both ternary and binary complexes (cTnICT and cTnIC) as well as cytosolic cTnI and cTnT, without cross-reactivity to skeletal forms.[11] 

Several biochemical markers were used to detect myocardial injury prior to the introduction of troponin.[12] Aspartate transaminase, lactate dehydrogenase, and creatine kinase served as diagnostic indicators during the 1960s and 1970s. However, these enzymes lacked specificity for cardiac tissue and were subsequently replaced.[13] The succeeding generation of biomarkers demonstrated greater cardiac specificity, including creatine kinase myocardial band and lactate dehydrogenase isoenzymes 1 and 2, yet still produced an unacceptably high false-positive rate, necessitating the identification of a more specific marker. Troponins were first described in 1965, but reliable immunoassays for their quantitative measurement in serum were not developed until the late 1990s.[14]

Troponin assays demonstrated near-complete sensitivity when performed 6 to 12 hours after symptom onset and exhibited markedly higher specificity for myocardial injury than earlier biomarkers. Owing to their diagnostic accuracy and prognostic value, serial troponin determinations were incorporated into the Fourth Universal Definition of Myocardial Infarction, the standard currently endorsed by the American College of Cardiology.[15]

Pathophysiology

Myocardial infarction results from obstruction of coronary blood flow, producing ischemia within the myocardium supplied by the affected vessel.[16] The ensuing imbalance between oxygen supply and myocardial oxygen demand leads to cellular hypoxia, necrosis, and myocyte death.[17] Disruption of cell membrane integrity during this process releases intracellular constituents into the interstitial space, which subsequently enter the systemic circulation.[18] These constituents, including cTns, become detectable in serum when released in sufficient quantity.

A basal concentration of troponin is present in the circulation of healthy individuals due to normal myocyte turnover.[19] Elevated troponin levels indicate pathologic myocardial injury when the measured value exceeds the 99th percentile of the reference population, approximately 3 standard deviations above the mean.[20] According to the Fourth Universal Definition of Myocardial Infarction, myocardial injury is defined by a cTn concentration above the 99th percentile upper reference limit (URL), characterized as acute when serial measurements demonstrate a rise, fall, or rise-and-fall pattern.[21]

Serum troponin concentrations typically rise within 2 to 3 hours after the onset of ischemic chest pain, reach peak between 12 and 48 hours, and gradually return to baseline within 4 to 10 days.[22] The characteristic temporal rise-and-fall pattern helps differentiate myocardial infarction from other causes of troponin elevation.[23] The intrinsic plasma half-life of both cTnI and cTnT is approximately 2 hours. However, continued release from necrotic myocardium yields an apparent half-life of approximately 24 hours, whereas cTnT shows a slightly longer duration.[24]

CTnT and cTnI possess amino acid sequences distinct from those of skeletal muscle isoforms and are encoded by separate genes.[25] Human cTnI contains an additional 31 amino acid residues at the amino terminus compared with skeletal muscle troponin I, conferring complete cardiac specificity.[26] Only 1 isoform of cTnI has been identified, and cTnI expression does not occur in healthy, regenerating, or diseased skeletal muscle of humans or animals.[27] CTnT is encoded by a distinct gene from that of skeletal muscle troponin T and contains an additional 11 amino-terminal residues that confer cardiac specificity.

Expression of cTnT isoforms in skeletal muscle has been documented in patients with muscular dystrophy, polymyositis, dermatomyositis, and end-stage renal disease.[28] For this reason, antibody selection in cTnT assay design requires careful optimization to prevent detection of noncardiac isoforms or immunoreactive proteins expressed in neuromuscular disorders, which may produce false-positive cTnT results unrelated to myocardial injury.[29]

Specimen Requirements and Procedure

Serum or heparinized plasma is the specimen type for most commercially available troponin assays, whereas whole blood is used in select point-of-care (POC) testing systems.[30] Multiple studies have demonstrated significant discrepancies between serum and plasma cTnI concentrations, with plasma values approximately 30% lower than corresponding serum concentrations.[31] Specimens obtained from patients receiving anticoagulant therapy may require extended clotting times before processing. Lower plasma cTnI concentrations may fail to detect early or small AMIs.[32]

Heparin binding to cTnI may reduce assay immunoreactivity, depending on the anticoagulant's concentration in collection tubes. For example, a concentration of 90 U/mL heparin has been associated with an estimated 20% decrease in measured cTnI levels.[33] This effect likely reflects alterations in the sample matrix. Conversely, decreases in measured cTnT concentrations in heparinized samples appear to result from interactions between negatively charged glycosaminoglycans and basic amino acid residues on the cTnT molecule.[34] Serial monitoring requires that the specimen type (serum or plasma) remain consistent for each patient.[35] 

Analytical reliability may be compromised by suboptimal preanalytical specimen handling practices, such as incomplete sample mixing during collection, insufficient centrifugation to separate red blood cells from serum or plasma, or premature processing, which can leave residual fibrin.[36] Current consensus recommendations specify a turnaround time of no more than 60 minutes for troponin measurement in patients presenting with chest pain, and laboratories are encouraged to maintain or improve this benchmark.[37]

Diagnostic Tests

Serial measurement of troponin from initial elevation through peak and subsequent decline is generally impractical in the emergency department setting. Rapid diagnostic assessment is required when patients present with chest pain to facilitate timely management decisions. Electrocardiographic (ECG) findings are used to classify myocardial infarction into 2 principal types: ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation myocardial infarction (NSTEMI).[38]

In STEMI, troponin concentrations are elevated in conjunction with specific ECG abnormalities, including ST-segment elevation greater than 1 mm in contiguous leads with reciprocal changes, newly developed left bundle branch block, or posterior ST-segment elevation identified on a posterior ECG.[39] Diagnostic interpretation and therapeutic intervention are straightforward in this context. The findings indicate acute occlusion of a major coronary artery, necessitating emergent coronary catheterization when available, or administration of thrombolytic therapy to restore perfusion to the affected myocardium.[40]

NSTEMI is characterized by myocardial injury with elevated troponin concentrations, without ECG changes diagnostic of STEMI.[41] NSTEMI typically reflects a smaller area of myocardial necrosis than STEMI, and immediate coronary catheterization is not routinely indicated.[42] Initial management is primarily medical, typically consisting of dual antiplatelet therapy and systemic anticoagulation with agents such as heparin.[43]

Diagnosing NSTEMI poses a greater challenge in the emergency department. Patients with ischemic chest pain may demonstrate normal initial troponin values and no diagnostic ECG changes, as troponin elevation may not occur until 2 to 3 hours after myocardial injury.[44] Consequently, serial troponin measurements obtained at 3- to 6-hour intervals are recommended for patients with suspected ischemic events and normal initial troponin concentrations.[45]

Testing Procedures

Multiple commercial assays are available for the measurement of cTns, along with several quantitative and semiquantitative POC methods. Contemporary assays for cTnT and cTnI employ 2- or 3-site immunoassay designs. All assays utilize a capture format in which an immobilized antibody specifically binds troponin present in serum or plasma. The bound troponin is subsequently complexed with a second antibody and, in some platforms, with a third antibody conjugated to an indicator molecule. Assay variations arise from differences in antibody type, epitope recognition sites, and the indicator molecule used for signal generation.[46]

CTnI assays are widely implemented in POC testing.[47] In a typical 2-site enzyme-linked immunosorbent assay (ELISA) for cTnI, heparinized whole blood or plasma is applied to a single-use cartridge containing an electrochemical sensor.[48] This step initiates dissolution of the monoclonal anti-cTnI antibody and a 2nd monoclonal anti-cTnI antibody conjugated to alkaline phosphatase (ALP) within the sample matrix. During incubation, cTnI in the specimen binds to the ALP-conjugated antibody and becomes immobilized on the sensor surface.[49] Wash buffer containing enzyme substrate is then introduced to remove unbound material, while the bound ALP catalyzes substrate conversion to an electrochemically active product. The resulting amperometric signal is directly proportional to the cTnI concentration in the sample.[50]

In another cartridge-based reader system, either blood anticoagulated with ethylenediaminetetraacetic acid (EDTA) or plasma is introduced into the sample port via a transfer pipette. Red blood cells are separated from plasma using an integrated filter, after which a fixed plasma volume is incubated with fluorescently labeled anti-cTnI antibodies.[51] The reaction mixture migrates along the device until the fluorescent antigen-antibody complex is immobilized within a defined detection zone, where fluorescence is measured.[52] The detected fluorescence intensity is directly proportional to the cTnI concentration in the specimen.[53]

Measurement of cTnT is based on a 1-step sandwich ELISA incorporating streptavidin-biotin technology and electrochemiluminescence detection.[54] During the initial incubation, cTnT from the specimen binds to a biotinylated monoclonal anti-cTnT antibody and a ruthenium-labeled monoclonal cTnT-specific antibody, forming a sandwich complex. Streptavidin-coated microparticles are then introduced, and the complex is immobilized on the solid phase through biotin-streptavidin interaction. The reaction mixture is aspirated into the measuring cell, where magnetic capture secures the microparticles to the electrode surface and removes unbound substances. Application of voltage to the electrode induces electrochemiluminescence.

A photomultiplier detects the emitted light, and results are quantified using a calibration curve derived from a 2-point calibration and a 5-point master curve encoded within the reagent barcode.[55] The emitted chemiluminescence is directly proportional to the cTnT concentration in the specimen. This method is performed quantitatively using automated analyzers or POC instruments.[56]

Hs-cTn testing was approved for clinical use in the US in 2017 and has demonstrated substantial diagnostic and exclusionary benefits for AMI.[57] These assays exhibit improved analytical sensitivity, achieving less than 10% imprecision at very low troponin concentrations. Hs-cTn assays must meet the analytical performance criteria defined by the International Federation of Clinical Chemistry and Laboratory Medicine Committee on Clinical Applications of Cardiac Biomarkers and the American Association for Clinical Chemistry Academy. These standards emphasize acceptable imprecision at the 99th-percentile URL and require that hs-cTn be measurable in at least 50% of men and women above the limit of detection in a reference healthy cohort.[58]

Two significant challenges hinder the interchangeability of troponin assays in clinical and research applications. The absence of a primary reference material for cTnI prevents assay standardization among manufacturers.[59] In addition, measured concentrations vary across assays because circulating cTnI exists in multiple molecular forms, and the antibodies used in different assays bind to distinct cTnI epitopes, even among assays produced by the same manufacturer.[60]

Interfering Factors

A limitation of using troponins for diagnosing AMI is that elevations may occur in a variety of nonischemic conditions.[61] Any process that causes myocardial injury can result in troponin release into the circulation. The most frequent cause is myocardial ischemia secondary to an imbalance between oxygen supply and demand, as observed in AMI.[62] However, several other conditions can produce a similar mismatch. Tachycardia, for instance, reduces diastolic filling time—the period during which coronary perfusion occurs—while simultaneously increasing myocardial oxygen consumption.[63] Likewise, patients in shock may experience decreased oxygen delivery due to low circulating volume. In this setting, elevated troponin concentrations correlate with adverse outcomes.[64]

Troponin surges may also result from myocardial injury unrelated to ischemia. Direct blunt chest trauma may cause significant myocardial cell disruption and consequent release of the biomarker. In a study of 333 patients with blunt thoracic trauma, increased troponin levels were observed in 144 (44%) of cases.[65][66] Inflammatory myocardial disorders, including viral myocarditis, and infiltrative conditions such as sarcoidosis, are likewise associated with troponin elevation.[67]

Troponin release may also occur in systemic processes outside the heart. For example, elevated levels of this cardiac analyte are frequently detected in patients with acute stroke who lack evidence of coronary artery disease.[68] This finding is thought to result from autonomic dysregulation following cerebrovascular injury, leading to excessive catecholamine release and myocardial injury.[69]

Another factor complicating troponin measurement in diagnosing AMI is CKD.[70] Patients with this condition frequently exhibit troponin levels exceeding the 99th percentile without clinical or imaging evidence of cardiac disease. The mechanism underlying this elevation remains unclear but is believed to involve structural cardiac abnormalities and chronic low-grade myocardial injury.[71] Some evidence suggests that renal function contributes to troponin clearance, although the cardiac protein has not been detected in urine. This finding complicates interpretation in patients with CKD presenting with chest pain and elevated troponin values.[72]

A meta-analysis of 14 studies demonstrated a marked reduction in the specificity of troponin elevations above the 99th percentile among individuals with CKD. Serial measurement is essential in this population to determine whether levels are stable or dynamic.[73] Troponin levels in CKD are typically stable. Therefore, a rise-and-fall pattern is more indicative of a cardiac etiology. A change of 20% or greater between serial values has been proposed as suggestive of acute cardiac injury, although supporting evidence is limited.[74] Hemolysis may also interfere with specific troponin immunoassays, yielding false-positive or false-negative results.[75]

Troponin bound to heparin yields lower measured plasma concentrations than serum values.[76] Additional sources of interference that can affect assay detection and result in falsely low troponin concentrations include ascorbic acid in immunoenzymometric assays employing ALP, biotin in assays utilizing biotinylated antibodies, streptokinase in the presence of streptavidin, and high titers of anti-ruthenium or anti-streptavidin antibodies in cTnT assays.[77] The extent of interference is method-dependent and varies among commercially available assays.[78] Diagnostic manufacturers specify in assay package inserts the upper limits beyond which interference from factors such as hemolysis, icterus, or lipemia may occur.[79]

Antibody specificity is a critical determinant of assay accuracy. A potential source of interference in sandwich-type immunometric troponin assays is the presence of endogenous antibodies directed against nonhuman proteins, referred to as "heterophile antibodies."[80] These antibodies are polyreactive natural or autoantibodies that bind heterogeneous and poorly defined antigens with low affinity and weak binding strength.[81] Rheumatoid factor, whether of natural or autoimmune origin, accounts for most heterophile antibody interference in immunoassays.

Endogenous antibodies that interfere with immunoassays are classified as heterophile antibodies when no specific immunogen is identified, and the antibody reacts with immunoglobulins from 2 or more species or exhibits rheumatoid factor activity.[82] In the case of rheumatoid factor, false-positive results arise when rheumatoid factor binds to the Fc-constant domain of antigen-antibody complexes, particularly when the detection antibody is labeled anti-human immunoglobulin G. Therefore, the presence of rheumatoid factor in serum can produce spurious troponin elevations. The use of antibody Fab fragments can prevent interference mediated by the Fc portion of intact antibodies.[83]

Human anti-animal antibodies (HAAA) are high-affinity, polyclonal antibodies produced against a specific animal immunogen, usually whole immunoglobulins of the IgG or IgM class.[84] These antibodies demonstrate strong, specific binding to antigens of a single chemical composition. They can compete with test antigens by cross-reacting with reagent antibodies of the same species, thereby generating false-positive signals. The most common subtype is human anti-mouse antibody (HAMA), though antibodies directed against rabbits, goats, sheep, and other species have been reported.[85] As with all assays employing murine antibodies, potential interference from HAMA must be considered.[86]

An increasingly recognized stimulus for HAMA production is exposure to mouse monoclonal antibodies used in diagnostic imaging and immune-targeted therapies.[87] In a study, 41% of patients treated with radiolabeled murine monoclonal antibodies developed HAMA within weeks of therapy.[88]

In addition to causing false-positive results, heterophile antibodies may also produce falsely low values if they bind to the variable regions of the capture antibody, thereby mimicking the target antigen and preventing troponin binding.[89] The most widely implemented strategy to minimize the effect of HAMA in commercial immunoassays is the incorporation of nonimmune mouse immunoglobulin (IgG), which neutralizes commonly encountered HAMA.[90] Laboratory approaches to investigate potential interference include testing a diluted specimen in a reagent containing nonimmune mouse IgG or repeating the analysis using an assay configured with reagent antibodies derived from different species.[91]

Autoantibodies may also interfere with troponin immunometric assay methods, producing either false-positive or false-negative results depending on whether the autoantibody-analyte complex partitions into the free or bound analyte fraction.[92] Bohner et al reported a false-negative cTnI result attributable to a circulating autoantibody, likely IgG, that bound cTnI with high affinity and inhibited its recognition by the 2-site immunoassay.[93]

Eriksson and colleagues subsequently reported that falsely low troponin values may occur in up to 3.5% of cases, indicated by cTnI recoveries of 10% or less. The interference was most pronounced at low troponin concentrations. Although the exact identity of the interfering substance remains undetermined, its estimated molecular weight of 100 to 200 kDa suggests a proteinaceous origin.[94]

Results, Reporting, and Critical Findings

The Fourth Universal Definition of Myocardial Infarction Expert Consensus Document refines the diagnostic criteria for myocardial infarction to reflect the widespread use of hs-cTn. Detection of a cTn concentration above the 99th-percentile URL defines myocardial injury.[95] The injury is classified as acute when cTn values exhibit a rise, fall, or both.

Type 1 myocardial infarction is characterized by a rise, fall, or rise and fall in cTn, with at least 1 value exceeding the 99th percentile, accompanied by at least 1 of the following features:

• Symptoms consistent with acute myocardial ischemia
• New ischemic changes on ECG
• Development of pathological Q waves
• Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality in a distribution consistent with ischemia
• Identification of a coronary thrombus by angiography, including intracoronary imaging, or by autopsy

Type 2 myocardial infarction involves a rise, fall, or rise and fall in cTn, with at least 1 value exceeding the 99th percentile, and evidence of an imbalance between myocardial oxygen supply and demand unrelated to coronary thrombosis. Diagnosis requires at least 1 of the following criteria:

• Symptoms consistent with acute myocardial ischemia
• New ischemic ECG changes
• Development of pathological Q waves
• Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality in a distribution consistent with ischemia

Troponin elevations due to nonischemic cardiac or systemic causes should be considered if the diagnostic criteria are not met. Systematic evaluation of the clinical picture, accompanying laboratory findings, and imaging results is essential to differentiate these entities. 

Cardiac Procedural Myocardial Injury

Cardiac procedural myocardial injury is defined as an increase in cTn values exceeding the 99th-percentile URL in patients with normal baseline concentrations (≤ 99th-percentile URL). In patients with baseline cTn values above the 99th-percentile URL, cardiac procedural myocardial injury is defined as a rise in cTn greater than 20% from baseline, provided that baseline concentrations are stable or declining.

Coronary intervention–related myocardial infarction is defined by an elevation of cTn values greater than 5 times the 99th percentile URL in patients with normal baseline concentrations. For patients with elevated preprocedural cTn levels that are stable (≤20% variation) or show a decrease, the postprocedural cTn must demonstrate a rise exceeding 20%. The absolute postprocedural value must remain at least 5 times the 99th-percentile URL. Additionally, 1 of the following criteria must be present:

• New ischemic ECG changes
• Development of new pathological Q waves
• Angiographic evidence of a procedural flow-limiting complication, such as coronary dissection, occlusion of a major epicardial artery or side branch, thrombus formation, collateral flow disruption, or distal embolization

Myocardial infarction related to coronary artery bypass grafting is defined as an elevation of cTn values greater than 10 times the 99th percentile URL in patients with normal baseline concentrations. In individuals with elevated preprocedural cTn levels that are stable (≤20% variation) or demonstrate a decline, the postprocedural cTn must rise by more than 20%. The absolute postprocedural value must still exceed 10 times the 99th percentile URL. In addition, 1 of the following criteria is required:

• Development of new pathological Q waves
• Angiographic documentation of new graft occlusion or new native coronary artery occlusion
• Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality in a distribution consistent with an ischemic mechanism

Careful interpretation of postprocedural troponin elevations is essential to distinguish procedural myocardial injury from myocardial infarction. Continuous vigilance and correlation with clinical, ECG, and imaging findings are critical for accurate diagnosis and optimal patient management.

Clinical Significance

Accurate diagnosis and management of cardiac events are critical components of emergency medicine practice. The development and widespread adoption of troponin testing have significantly influenced diagnostic and therapeutic approaches in the emergency department. Recognition of the test’s analytical limitations and the need to interpret results within the broader clinical context remain essential for sound medical decision-making.[96] Troponin testing continues to shape contemporary emergency practice, underscoring the importance of a comprehensive understanding of its diagnostic and prognostic implications.

Elevated troponin concentrations must be interpreted in conjunction with clinical findings.[97] Nonischemic causes of troponin elevation include myocarditis, pericarditis, cardiac contusion or trauma, aortic dissection, endocarditis, cardiac surgery, pulmonary embolism, stroke (ischemic or hemorrhagic), cardiopulmonary resuscitation, defibrillation, chronic severe heart failure, cardiac arrhythmias (tachyarrhythmias, bradyarrhythmias, heart blocks), sepsis, renal failure, hypertrophic obstructive cardiomyopathy, takotsubo cardiomyopathy, burns, extreme exertion, infiltrative diseases such as amyloidosis, certain medications (eg, doxorubicin, trastuzumab), snake envenomation, transplant vasculopathy, and critical illness.[98]

Quality Control and Lab Safety

For nonwaived tests, laboratory regulations require analysis of at least 2 levels of control materials at least once every 24 hours.[99] Laboratories may increase the frequency of quality control testing to ensure the ongoing accuracy and reliability of results. Quality control samples must also be analyzed after instrument calibration or maintenance to verify acceptable analytical performance.[100]

Laboratories may implement an individualized quality control plan when manufacturer recommendations for quality control frequency are less stringent than regulatory requirements (eg, monthly testing). This approach involves conducting a comprehensive risk assessment of potential sources of error across all phases of testing and establishing a quality control plan to minimize the probability of error.[101] The Westgard multirule system is commonly applied to evaluate quality control results. Any rule violation necessitates appropriate corrective and preventive action before the release of patient test results.[102]

Participation in external quality control or proficiency testing programs is mandated under the Clinical and Laboratory Improvement Amendments (CLIA) regulations published by the Centers for Medicare & Medicaid Services (CMS).[103] These programs are essential for ensuring the accuracy and reliability of laboratory results by comparing results with those from other facilities performing equivalent assays. The CMS and voluntary accreditation organizations monitor participation and performance outcomes.[104] The proficiency testing plan should be incorporated into the laboratory’s quality assessment plan and overall quality management system.[105]

Quality assurance procedures must be maintained within the laboratory to ensure reliable, reproducible performance of troponin assays, particularly at low analyte concentrations, and to prevent the reporting of falsely positive results. In addition to monitoring manufacturer-supplied quality controls, daily analysis of a negative control sample and a low-level control with a troponin concentration near the 20% coefficient-of-variation threshold (either in-house or commercially prepared) enables detection of assay drift or declining analytical performance.[106] Long-term monitoring of troponin assay imprecision should also account for new reagent lots, formulation changes, and suboptimal analyzer performance to sustain method stability and accuracy over time.[107]

All specimens, controls, and calibrators must be regarded as potentially infectious. Standard precautions should be observed when handling all laboratory reagents. Waste disposal must comply with institutional and local regulatory guidelines.[108] Appropriate personal protective equipment, including gloves, a laboratory coat, and safety glasses, should be worn when handling human blood specimens.

All plastic pipette tips, sample cups, and gloves that come into contact with blood must be discarded into biohazard waste containers.[109] Disposable glassware should be placed in designated sharps containers. Work surfaces must be protected with disposable absorbent bench paper, which must be replaced weekly or immediately following blood contamination. All bench surfaces should be decontaminated weekly.[110] The analytical standard for hs-cTn assays is defined by the ability to measure troponin concentrations with a coefficient of variation less than 10% at or below the 99th percentile URL and to achieve measurable values in more than 50% of healthy individuals.[111]

Enhancing Healthcare Team Outcomes

The interpretation and management of elevated cTn levels require close collaboration among healthcare professionals to ensure timely diagnosis, appropriate treatment, and patient safety. Physicians, advanced practitioners, nurses, pharmacists, and laboratory staff each play a critical role in delivering coordinated, patient-centered care.

Physicians and advanced practitioners are responsible for clinical assessment, integrating troponin results with patient history, ECG findings, and imaging studies to differentiate AMI from nonischemic causes, including CKD, sepsis, and myocarditis. The care team must apply evidence-based guidelines to prevent overdiagnosis and avoid unnecessary interventions while ensuring that acute coronary syndromes are managed promptly.

All healthcare personnel, including advanced practice providers, should be knowledgeable about biomarkers of myocardial infarction. Nevertheless, history and physical examination remain indispensable.[112] Definitive confirmation of AMI requires additional evaluation, including ECG, echocardiography, and chest radiography. Reliance on a single serum assay is insufficient due to the potential for false-positive and false-negative results.[113]

Nurses play a critical role in the early recognition of symptoms indicative of myocardial ischemia, accurate specimen collection and labeling, and monitoring for complications, including arrhythmias and progression of chest pain. The responsibilities of these healthcare personnel also include maintaining precise communication with the laboratory and medical teams regarding specimen timing, given the importance of troponin kinetics in serial testing protocols.

Clinical laboratory professionals ensure the analytical accuracy and reliability of troponin assays by verifying quality control, minimizing preanalytical errors, and flagging results that require clinical interpretation. Pharmacists contribute by reviewing concomitant medications, managing anticoagulant and antiplatelet therapies, and preventing drug interactions that may exacerbate myocardial injury or affect the accuracy of cardiac testing. 

Ethical practice and precise communication are essential in managing elevated troponin results. Team members must review findings collaboratively to prevent overdiagnosis, unnecessary procedures, or patient distress. Interprofessional discussions, joint rounds, and thorough electronic health record documentation ensure that all members of the care team share a consistent understanding of the patient’s condition and treatment plan.

Coordinated collaboration enhances diagnostic accuracy, reduces unnecessary testing, and improves patient outcomes. Through mutual respect, effective communication, and shared responsibility, the healthcare team can manage elevated troponin levels efficiently while maintaining optimal standards of patient safety and care quality.

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Disclosure: Muhammad Zubair declares no relevant financial relationships with ineligible companies.

Disclosure: Sandeep Sharma declares no relevant financial relationships with ineligible companies.