General

Synonym/Acronym:
Cardiac troponin, cardiac troponin I (cTnI), cardiac troponin T (cTnT).

Common Use:
To assist in evaluating myocardial muscle damage related to disorders such as myocardial infarction.

Specimen:
Serum (1 mL) collected in a red- or tiger-top tube. Plasma (1 mL) collected in a green-top (heparin) tube is also acceptable. Serial sampling is highly recommended. Care must be taken to use the same type of collection container if serial measurements are to be taken.

Normal Findings:
(Method: Enzyme immunoassay)

Troponin I
 0–30 dLess than 4.8 ng/mL
 1–3 moLess than 0.4 ng/mL
 3–6 moLess than 0.3 ng/mL
 7–12 moLess than 0.2 ng/mL
 1–18 yrLess than 0.1 ng/mL
 AdultLess than 0.05 ng/mL
Troponin TLess than 0.2 ng/mL
Normal values can vary significantly due to differences in test kit reagents and instrumentation. The testing laboratory should be consulted for comparison of results to the corresponding reference range.

Description

Troponin is a complex of three contractile proteins that regulate the interaction of actin and myosin. Troponin C is the calcium-binding subunit; it does not have a cardiac muscle–specific subunit. Troponin I and troponin T, however, do have cardiac muscle–specific subunits. They are detectable a few hours to 7 days after the onset of symptoms of myocardial damage. Troponin I is thought to be a more specific marker of cardiac damage than troponin T. Cardiac troponin I begins to rise 2 to 6 hr after myocardial infarction (MI). It has a biphasic peak: It initially peaks at 15 to 24 hr after MI and then exhibits a lower peak after 60 to 80 hr. Cardiac troponin T levels rise 2 to 6 hr after MI and remain elevated. Both proteins return to the reference range 7 days after MI.
Timing for Appearance and Resolution of Serum/Plasma Cardiac Markers in Acute MI
Cardiac MarkerAppearance (hr)Peak (hr)Resolution (days)
AST6–824–483–4
CK (total)4–6242–3
Cardiac MarkerAppearance (hr)Peak (hr)Resolution (days)
CK-MB4–615–202–3
LDH1224–4810–14
Myoglobin1–34–121
Troponin I2–615–205–7
AST = aspartate aminotransferase; CK = creatine kinase; CK-MB = creatine kinase MB fraction; LDH = lactate dehydrogenase.

Indications

  • Assist in establishing a diagnosis of MI
  • Evaluate myocardial cell damage

Potential Diagnosis

Increased In:

Conditions that result in cardiac tissue damage; troponin is released from damaged tissue into the circulation.

  • Acute MI
  • Minor myocardial damage
  • Myocardial damage after coronary artery bypass graft surgery or percutaneous transluminal coronary angioplasty
  • Unstable angina pectoris

Decreased In:
N/A

Critical Findings

N/A

Interfering Factors

N/A

Nursing Implications Procedure

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patientthis test can assist in evaluating heart damage.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s cardiovascular system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values).
  • Review the procedure with the patient. Inform the patient that a number of samples will be collected. Collection at time of admission, 2 to 4 hr, 6 to 8 hr, and 12 hr after admission are the minimal recommendations. Additional samples may be requested. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • There are no food, fluid, or medication restrictions unless by medical direction.

Intratest

  • If the patient has a history of allergic reaction to latex, avoid the use of equipment containing latex.
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
  • Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
  • Promptly transport the specimen to the laboratory for processing and analysis.

Post Test

  • A report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • Nutritional Considerations: Increased troponin levels are associated with coronary artery disease (CAD). The American Heart Association and National Heart, Lung, and Blood Institute (NHLBI) recommend nutritional therapy for individuals identified to be at high risk for developing CAD or individuals who have specific risk factors and/or existing medical conditions (e.g., elevated LDL cholesterol levels, other lipid disorders, insulin-dependent diabetes, insulin resistance, or metabolic syndrome). If overweight, the patient should be encouraged to achieve a normal weight. Guidelines for the Therapeutic Lifestyle Changes (TLC) diet are outlined in the Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III [ATP III]). The TLC diet emphasizes a reduction in foods high in saturated fats and cholesterol. Red meats, eggs, and dairy products are the major sources of saturated fats and cholesterol. If triglycerides also are elevated, the patient should be advised to eliminate or reduce alcohol and simple carbohydrates from the diet. The TLC approach also includes the use of plant stanols or sterols and increased dissolved fiber as an option for lowering LDL cholesterol levels; nutritional recommendations for daily total caloric intake; recommendations for allowable percentage of calories derived from fat (saturated and unsaturated), carbohydrates, protein, and cholesterol; as well as recommendations for daily expenditure of energy.
  • Nutritional Considerations: Overweight patients with high blood pressure should be encouraged to achieve a normal weight. Other changeable risk factors warranting patient education include strategies to safely decrease sodium intake, increase physical activity, decrease alcohol consumption, eliminate tobacco use, and decrease cholesterol levels.
  • Social and Cultural Considerations: Numerous studies point to the prevalence of excess body weight in American children and adolescents. Experts estimate that obesity is present in 25% of the population ages 6 to 11 yr. The medical, social, and emotional consequences of excess body weight are significant. Special attention should be given to instructing the child and caregiver regarding health risks and weight-control education.
  • Recognize anxiety related to test results, and be supportive of fear of shortened life expectancy. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate. Educate the patient regarding access to counseling services. Provide contact information, if desired, for the American Heart Association (www.americanheart.org) or the NHLBI (www.nhlbi.nih.gov).
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.