Troponin test
Encyclopedia
The troponin test can be used as a test of several different heart disorders, including myocardial infarction
.
(cardiac troponin I
and T
) are very sensitive and specific indicators
of damage to the heart
muscle (myocardium). They are measured in the blood
to differentiate between unstable angina and myocardial infarction
(heart attack) in patients with chest pain
or acute coronary syndrome
. A patient who had suffered from a myocardial infarction would have an area of damaged heart muscle and so would have elevated cardiac troponin levels in the blood. This can also occur in patients with coronary vasospasm
.
It is important to note that cardiac troponins are a marker of all heart muscle damage, not just myocardial infarction. Other conditions that directly or indirectly lead to heart muscle damage can also increase troponin levels. Severe tachycardia
(for example due to supraventricular tachycardia
) in an individual with normal coronary arteries can also lead to increased troponins for example, presumably due to increased oxygen demand and inadequate supply to the heart muscle.
Troponins are also increased in patients with heart failure, where they also predict mortality and ventricular rhythm abnormalities. They can rise in inflammatory conditions such as myocarditis
and pericarditis
with heart muscle involvement (which is then termed myopericarditis). Troponins can also indicate several forms of cardiomyopathy
, such as dilated cardiomyopathy
, hypertrophic cardiomyopathy
or (left) ventricular hypertrophy
, peripartum cardiomyopathy
, Takotsubo cardiomyopathy
or infiltrative disorders such as cardiac amyloidosis
.
Heart injury with increased troponins also occurs in cardiac contusion, defibrillation
and internal or external cardioversion
. Increased troponins are commonly increased in several procedures such as cardiac surgery
and heart transplantation, closure of atrial septal defect
s, percutaneous coronary intervention
or radiofrequency ablation
.
Troponins are increased in around 40% of patients with critical illness
es such as sepsis
. There is an increased risk of mortality and length of stay in the intensive care unit in these patients. In severe gastrointestinal bleeding
there can also be a mismatch between oxygen demand and supply of the myocardium.
Chemotherapy agents can exert toxic effects on the heart (examples include anthracycline
, cyclophosphamide
, 5-fluorouracil and cisplatin
). Several toxins and venoms can also lead to heart muscle injury (scorpion venom, snake venom
, venom from jellyfish or centipede
s). Carbon monoxide poisoning
or cyanide poisoning
can also be accompanied by release of troponins due to hypoxic cardiotoxic effects. Cardiac injury occurs in about one third of severe CO poisoning cases, and troponin screening is appropriate in these patients.
Some patients with dissection of the ascending aorta
have elevated troponins, and increased hemodynamic stress has been suggested as a mechanism.
In both primary pulmonary hypertension
, pulmonary embolism
and acute exacerbations of chronic obstructive pulmonary disease
(COPD), right ventricular
strain with increased wall tension and ischemia. Of course, patients with COPD exacerbations might also have concurrent myocardial infarction or pulmonary embolism, so care has to be taken to attribute increased troponin levels to COPD.
Central nervous system
disorders can lead to increased sympathetic
tone and/or catecholamine
release which lead to cardiac overstimulation. This is seen in subarachnoid hemorrhage
, stroke
, intracranial hemorrhage
and (generalized) seizure
s (in patients with epilepsy
or eclampsia
, for example).
Patients with end-stage renal disease can have chronically elevated troponin T levels, which are linked to a poorer prognosis. Troponin I is less likely to be falsely elevated.
Strenuous endurance exercise such as marathons or triathlon
s can lead to increased troponin levels in up to one third of subjects, but it is not linked to adverse health effects in these competitors.
High troponin T levels have also been reported in patients with inflammatory muscle diseases such as polymyositis
or dermatomyositis
. Troponins are also increased in rhabdomyolysis
.
In hypertensive disorders of pregnancy such as preeclampsia, elevated troponin levels indicate some degree of myofibrillary damage.
Cardiac troponin T and I can be used to monitor drug and toxin induced cardiomyocyte toxicity. .
methods..
In a community-based cohort study indicating the importance of silent cardiac damage, troponin I has been shown to predict mortality and first coronary heart disease event in men free from cardiovascular disease at baseline.
Myocardial infarction
Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
.
Cardiac conditions
Certain subtypes of troponinTroponin
400px|thumb|right|alt = Colored dice with checkered background|Ribbon representation of the human cardiac troponin core complex in the calcium-saturated form...
(cardiac troponin I
Troponin I
Troponin I is a part of the troponin complex. It binds to actin in thin myofilaments to hold the actin-tropomyosin complex in place. Because of it myosin cannot bind actin in relaxed muscle...
and T
Troponin T
Troponin T is a part of the troponin complex. It binds to tropomyosin, interlocking them to form a troponin-tropomyosin complex.The tissue specific subtypes are:* Slow skeletal troponin T1, TNNT1 * Cardiac troponin T2, TNNT2...
) are very sensitive and specific indicators
Cardiac markers
Cardiac markers are biomarkers measured to evaluate heart function. They are often discussed in the context of myocardial infarction, but other conditions can lead to an elevation in cardiac marker level....
of damage to the heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
muscle (myocardium). They are measured in the blood
Blood test
A blood test is a laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a needle, or via fingerprick....
to differentiate between unstable angina and myocardial infarction
Myocardial infarction
Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
(heart attack) in patients with chest pain
Chest pain
Chest pain may be a symptom of a number of serious conditions and is generally considered a medical emergency. Even though it may be determined that the pain is non-cardiac in origin, this is often a diagnosis of exclusion made after ruling out more serious causes of the pain.-Differential...
or acute coronary syndrome
Acute coronary syndrome
Acute coronary syndrome is usually one of three diseases involving the coronary arteries: ST elevation myocardial infarction , non ST elevation myocardial infarction , or unstable angina ....
. A patient who had suffered from a myocardial infarction would have an area of damaged heart muscle and so would have elevated cardiac troponin levels in the blood. This can also occur in patients with coronary vasospasm
Coronary vasospasm
Coronary vasospasm is a form of vasospasm affecting the coronary circulation.It can cause Prinzmetal's angina.It can occur in multiple vessels.Atropine has been used to treat the condition....
.
It is important to note that cardiac troponins are a marker of all heart muscle damage, not just myocardial infarction. Other conditions that directly or indirectly lead to heart muscle damage can also increase troponin levels. Severe tachycardia
Tachycardia
Tachycardia comes from the Greek words tachys and kardia . Tachycardia typically refers to a heart rate that exceeds the normal range for a resting heart rate...
(for example due to supraventricular tachycardia
Supraventricular tachycardia
Supraventricular tachycardia is a general term that refers to any rapid heart rhythm originating above the ventricular tissue. Supraventricular tachycardias can be contrasted to the potentially more dangerous ventricular tachycardias - rapid rhythms that originate within the ventricular...
) in an individual with normal coronary arteries can also lead to increased troponins for example, presumably due to increased oxygen demand and inadequate supply to the heart muscle.
Troponins are also increased in patients with heart failure, where they also predict mortality and ventricular rhythm abnormalities. They can rise in inflammatory conditions such as myocarditis
Myocarditis
Myocarditis is inflammation of heart muscle . It resembles a heart attack but coronary arteries are not blocked.Myocarditis is most often due to infection by common viruses, such as parvovirus B19, less commonly non-viral pathogens such as Borrelia burgdorferi or Trypanosoma cruzi, or as a...
and pericarditis
Pericarditis
Pericarditis is an inflammation of the pericardium . A characteristic chest pain is often present.The causes of pericarditis are varied, including viral infections of the pericardium, idiopathic causes, uremic pericarditis, bacterial infections of the precardium Pericarditis is an inflammation of...
with heart muscle involvement (which is then termed myopericarditis). Troponins can also indicate several forms of cardiomyopathy
Cardiomyopathy
Cardiomyopathy, which literally means "heart muscle disease," is the deterioration of the function of the myocardium for any reason. People with cardiomyopathy are often at risk of arrhythmia or sudden cardiac death or both. Cardiomyopathy can often go undetected, making it especially dangerous to...
, such as dilated cardiomyopathy
Dilated cardiomyopathy
Dilated cardiomyopathy or DCM is a condition in which the heart becomes weakened and enlarged and cannot pump blood efficiently. The decreased heart function can affect the lungs, liver, and other body systems....
, hypertrophic cardiomyopathy
Hypertrophic cardiomyopathy
Hypertrophic cardiomyopathy is a disease of the myocardium in which a portion of the myocardium is hypertrophied without any obvious cause...
or (left) ventricular hypertrophy
Ventricular hypertrophy
Ventricular hypertrophy is the enlargement of ventricles in the heart. Although left ventricular hypertrophy is more common, enlargement can also occur in the right ventricle, or both ventricles.- Physiology :...
, peripartum cardiomyopathy
Peripartum cardiomyopathy
Peripartum cardiomyopathy is a form of dilated cardiomyopathy that is defined as deterioration in cardiac function presenting typically between the last month of pregnancy and up to five months postpartum...
, Takotsubo cardiomyopathy
Takotsubo cardiomyopathy
Takotsubo cardiomyopathy, also known as transient apical ballooning syndrome, apical ballooning cardiomyopathy, stress-induced cardiomyopathy, Gebrochenes-Herz-Syndrom, and simply stress cardiomyopathy, is a type of non-ischemic cardiomyopathy in which there is a sudden temporary weakening of the...
or infiltrative disorders such as cardiac amyloidosis
Amyloidosis
In medicine, amyloidosis refers to a variety of conditions whereby the body produces "bad proteins", denoted as amyloid proteins, which are abnormally deposited in organs and/or tissues and cause harm. A protein is described as being amyloid if, due to an alteration in its secondary structure, it...
.
Heart injury with increased troponins also occurs in cardiac contusion, defibrillation
Defibrillation
Defibrillation is a common treatment for life-threatening cardiac arrhythmias, ventricular fibrillation and pulseless ventricular tachycardia. Defibrillation consists of delivering a therapeutic dose of electrical energy to the affected heart with a device called a defibrillator...
and internal or external cardioversion
Cardioversion
Cardioversion is a medical procedure by which an abnormally fast heart rate or cardiac arrhythmia is converted to a normal rhythm, using electricity or drugs. Synchronized electrical cardioversion uses a therapeutic dose of electric current to the heart, at a specific moment in the cardiac cycle...
. Increased troponins are commonly increased in several procedures such as cardiac surgery
Cardiothoracic Surgery
Cardiothoracic surgery is the field of medicine involved in surgical treatment of diseases affecting organs inside the thorax —generally treatment of conditions of the heart and lungs .-Cardiac / Thoracic:...
and heart transplantation, closure of atrial septal defect
Atrial septal defect
Atrial septal defect is a form of congenital heart defect that enables blood flow between the left and right atria via the interatrial septum. The interatrial septum is the tissue that divides the right and left atria...
s, percutaneous coronary intervention
Angioplasty
Angioplasty is the technique of mechanically widening a narrowed or obstructed blood vessel, the latter typically being a result of atherosclerosis. An empty and collapsed balloon on a guide wire, known as a balloon catheter, is passed into the narrowed locations and then inflated to a fixed size...
or radiofrequency ablation
Radiofrequency ablation
Radio frequency ablation is a medical procedure where part of the electrical conduction system of the heart, tumor or other dysfunctional tissue is ablated using the heat generated from the high frequency alternating current to treat a medical disorder...
.
Non-cardiac conditions
The distinction between cardiac and non-cardiac conditions is somewhat artificial; the conditions listed below are not primary heart diseases, but they exert indirect effects on the heart muscle.Troponins are increased in around 40% of patients with critical illness
Intensive care medicine
Intensive-care medicine or critical-care medicine is a branch of medicine concerned with the diagnosis and management of life threatening conditions requiring sophisticated organ support and invasive monitoring.- Overview :...
es such as sepsis
Sepsis
Sepsis is a potentially deadly medical condition that is characterized by a whole-body inflammatory state and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues...
. There is an increased risk of mortality and length of stay in the intensive care unit in these patients. In severe gastrointestinal bleeding
Gastrointestinal bleeding
Gastrointestinal bleeding or gastrointestinal hemorrhage describes every form of hemorrhage in the gastrointestinal tract, from the pharynx to the rectum. It has diverse causes, and a medical history, as well as physical examination, generally distinguishes between the main forms...
there can also be a mismatch between oxygen demand and supply of the myocardium.
Chemotherapy agents can exert toxic effects on the heart (examples include anthracycline
Anthracycline
Anthracyclines are a class of drugs used in cancer chemotherapy derived from Streptomyces bacterium Streptomyces peucetius var...
, cyclophosphamide
Cyclophosphamide
Cyclophosphamide , also known as cytophosphane, is a nitrogen mustard alkylating agent, from the oxazophorines group....
, 5-fluorouracil and cisplatin
Cisplatin
Cisplatin, cisplatinum, or cis-diamminedichloroplatinum is a chemotherapy drug. It is used to treat various types of cancers, including sarcomas, some carcinomas , lymphomas, and germ cell tumors...
). Several toxins and venoms can also lead to heart muscle injury (scorpion venom, snake venom
Snake venom
Snake venom is highly modified saliva that is produced by special glands of certain species of snakes. The glands which secrete the zootoxin are a modification of the parotid salivary gland of other vertebrates, and are usually situated on each side of the head below and behind the eye,...
, venom from jellyfish or centipede
Centipede
Centipedes are arthropods belonging to the class Chilopoda of the subphylum Myriapoda. They are elongated metameric animals with one pair of legs per body segment. Despite the name, centipedes can have a varying number of legs from under 20 to over 300. Centipedes have an odd number of pairs of...
s). Carbon monoxide poisoning
Carbon monoxide poisoning
Carbon monoxide poisoning occurs after enough inhalation of carbon monoxide . Carbon monoxide is a toxic gas, but, being colorless, odorless, tasteless, and initially non-irritating, it is very difficult for people to detect...
or cyanide poisoning
Cyanide poisoning
Cyanide poisoning occurs when a living organism is exposed to a compound that produces cyanide ions when dissolved in water. Common poisonous cyanide compounds include hydrogen cyanide gas and the crystalline solids potassium cyanide and sodium cyanide...
can also be accompanied by release of troponins due to hypoxic cardiotoxic effects. Cardiac injury occurs in about one third of severe CO poisoning cases, and troponin screening is appropriate in these patients.
Some patients with dissection of the ascending aorta
Aortic dissection
Aortic dissection occurs when a tear in the inner wall of the aorta causes blood to flow between the layers of the wall of the aorta and force the layers apart. The dissection typically extends anterograde, but can extend retrograde from the site of the intimal tear. Aortic dissection is a medical...
have elevated troponins, and increased hemodynamic stress has been suggested as a mechanism.
In both primary pulmonary hypertension
Pulmonary hypertension
In medicine, pulmonary hypertension is an increase in blood pressure in the pulmonary artery, pulmonary vein, or pulmonary capillaries, together known as the lung vasculature, leading to shortness of breath, dizziness, fainting, and other symptoms, all of which are exacerbated by exertion...
, pulmonary embolism
Pulmonary embolism
Pulmonary embolism is a blockage of the main artery of the lung or one of its branches by a substance that has travelled from elsewhere in the body through the bloodstream . Usually this is due to embolism of a thrombus from the deep veins in the legs, a process termed venous thromboembolism...
and acute exacerbations of chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease , also known as chronic obstructive lung disease , chronic obstructive airway disease , chronic airflow limitation and chronic obstructive respiratory disease , is the co-occurrence of chronic bronchitis and emphysema, a pair of commonly co-existing diseases...
(COPD), right ventricular
Right ventricle
The right ventricle is one of four chambers in the human heart. It receives deoxygenated blood from the right atrium via the tricuspid valve, and pumps it into the pulmonary artery via the pulmonary valve and pulmonary trunk....
strain with increased wall tension and ischemia. Of course, patients with COPD exacerbations might also have concurrent myocardial infarction or pulmonary embolism, so care has to be taken to attribute increased troponin levels to COPD.
Central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
disorders can lead to increased sympathetic
Sympathetic nervous system
The sympathetic nervous system is one of the three parts of the autonomic nervous system, along with the enteric and parasympathetic systems. Its general action is to mobilize the body's nervous system fight-or-flight response...
tone and/or catecholamine
Catecholamine
Catecholamines are molecules that have a catechol nucleus consisting of benzene with two hydroxyl side groups and a side-chain amine. They include dopamine, as well as the "fight-or-flight" hormones adrenaline and noradrenaline released by the adrenal medulla of the adrenal glands in response to...
release which lead to cardiac overstimulation. This is seen in subarachnoid hemorrhage
Subarachnoid hemorrhage
A subarachnoid hemorrhage , or subarachnoid haemorrhage in British English, is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain...
, stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
, intracranial hemorrhage
Intracranial hemorrhage
An intracranial hemorrhage is a hemorrhage, or bleeding, within the skull.-Causes:Intracranial bleeding occurs when a blood vessel within the skull is ruptured or leaks. It can result from physical trauma or nontraumatic causes such as a ruptured aneurysm...
and (generalized) seizure
Seizure
An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement or as mild as a brief loss of awareness...
s (in patients with epilepsy
Epilepsy
Epilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...
or eclampsia
Eclampsia
Eclampsia , an acute and life-threatening complication of pregnancy, is characterized by the appearance of tonic-clonic seizures, usually in a patient who had developed pre-eclampsia...
, for example).
Patients with end-stage renal disease can have chronically elevated troponin T levels, which are linked to a poorer prognosis. Troponin I is less likely to be falsely elevated.
Strenuous endurance exercise such as marathons or triathlon
Triathlon
A triathlon is a multi-sport event involving the completion of three continuous and sequential endurance events. While many variations of the sport exist, triathlon, in its most popular form, involves swimming, cycling, and running in immediate succession over various distances...
s can lead to increased troponin levels in up to one third of subjects, but it is not linked to adverse health effects in these competitors.
High troponin T levels have also been reported in patients with inflammatory muscle diseases such as polymyositis
Polymyositis
Polymyositis is a type of chronic inflammation of the muscles related to dermatomyositis and inclusion body myositis.-Signs and symptoms:...
or dermatomyositis
Dermatomyositis
Dermatomyositis is a connective-tissue disease related to polymyositis and Bramaticosis that is characterized by inflammation of the muscles and the skin.- Causes :...
. Troponins are also increased in rhabdomyolysis
Rhabdomyolysis
Rhabdomyolysis is a condition in which damaged skeletal muscle tissue breaks down rapidly. Breakdown products of damaged muscle cells are released into the bloodstream; some of these, such as the protein myoglobin, are harmful to the kidneys and may lead to kidney failure...
.
In hypertensive disorders of pregnancy such as preeclampsia, elevated troponin levels indicate some degree of myofibrillary damage.
Cardiac troponin T and I can be used to monitor drug and toxin induced cardiomyocyte toxicity. .
Detection of cardiac troponin
Cardiac troponin T and I are measured by immunoassayImmunoassay
An immunoassay is a biochemical test that measures the presence or concentration of a substance in solutions that frequently contain a complex mixture of substances. Analytes in biological liquids such as serum or urine are frequently assayed using immunoassay methods...
methods..
- Due to patent regulations a single manufacturer (Roche Diagnositcs) distributes cTnT.
- A host of diagnostic companies make cTnI immunoassay methods available on many different immunoassay platforms.
Prognostic use
Raised troponin levels are prognostically important in many of the conditions in which they are used for diagnosis.In a community-based cohort study indicating the importance of silent cardiac damage, troponin I has been shown to predict mortality and first coronary heart disease event in men free from cardiovascular disease at baseline.