The key difference between troponin and CK-MB is that troponin is a protein that stays elevated for 1-2 weeks after myocardial infarction, while CK-MB is a protein that stays elevated for 1 to 2 days after myocardial infarction.
Myocardial infarction, also known as a heart attack, is caused by decreased or complete stopping of blood flow to a part of the myocardium. It can be diagnosed through different blood tests. These blood tests are based on detecting the concentration of some proteins in the blood. Troponin and CK-MB are two proteins mainly found in heart muscles. They can also be found in skeletal muscles but not in smooth muscles. When the heart is damaged, their levels in the blood keep increasing. Therefore, troponin and CK-MB blood tests can be used to diagnose myocardial infarction.
CONTENTS
1. Overview and Key Difference
2. What is Troponin
3. What is CK-MB (Creatine Kinase-MB)
4. Similarities – Troponin and CK-MB
5. Troponin vs. CK-MB in Tabular Form
6. Summary – Troponin vs. CK-MB
What is Troponin?
Troponin is a protein found in certain types of muscles (heart muscle and smooth) in the body. In normal circumstances, this protein exists inside muscle cells, and only small concentrations of it circulate in the bloodstream freely. However, when the heart is damaged, it causes more troponin to escape into the blood. There are normally two types of troponin: troponin I (cTnI) and troponin T (cTnT). Troponin I is a kind of troponin that is unique to the heart muscle. Troponin T can be mainly found in heart muscles but does exist in other types of muscles, such as smooth muscles.
Figure 01: Troponin
In addition to heart attack, troponin level also increases in other conditions and situations such as chronic kidney disease, pulmonary embolism, congestive heart failure, heart surgery, heart valve disease, irregular heart rhythms, sepsis, exercising too much strenuously, and extreme emotional strain like stress. Furthermore, normal levels of troponin I in the blood are 0 – 0.04 ng/mL, and normal levels of troponin T are 0 – 0.01 ng/mL.
What is CK-MB?
Creatine Kinase-MB (CK-MB) is a form of cardiac enzyme found primarily in heart muscle cells. But a small amount of CK-MB can also be found in smooth muscles. There are two different isoforms of CK-MB; they are CK-MB1 and CK-MB2. It is a cardiac marker. Therefore, this protein is usually used to assist in the diagnosis of conditions such as acute myocardial infarction, myocardial ischemia, or myocarditis. However, CK-MB level also increases in the blood due to other conditions like cardiac malformations (ventricular septal defects) in newborns and autoimmune reactions.
Figure 02: CK-MB
Moreover, the normal reference ranges of CKMB in the blood are less than 4.4 ng/mL for women or people assigned female at birth (AFAB) and less than 7.8 ng/mL for men and people assigned male at birth (AMAB).
What are the Similarities Between Troponin and CK-MB?
- Troponin and CK-MB are two proteins or enzymes in cardiac muscles.
- Both proteins are also found in skeletal muscles but are absent in smooth muscles.
- They have different forms.
- The levels of both proteins in the blood can be used to diagnose myocardial infarction and other medical conditions.
What is the Difference Between Troponin and CK-MB?
Troponin is a protein that stays elevated for 1-2 weeks after myocardial infarction, while CK-MB is a protein that stays elevated for 1 to 2 days after myocardial infarction. Thus, this is the key difference between troponin and CK-MB. Furthermore, the molecular weight of troponin is approximately 23.9 kDa. On the other hand, the molecular weight of CK-MB is approximately 87 kDa. Moreover, troponin is a protein that has 209 amino acids in its structure, while CK-MB has 381 amino acids in its structure.
The infographic below presents the differences between troponin and CK-MB in tabular form for side-by-side comparison.
Summary – Troponin vs CK-MB
Myocardial infarction is a deadly condition where the heart muscle begins to die due to not getting enough blood flow. It happens due to the blockage in the arteries that supply blood to the heart. If it doesn’t restore blood flow soon, a myocardial infarction or heart attack can cause permanent heart damage or death. Myocardial infarction can be diagnosed by detecting the levels of certain proteins, such as troponin and CK-MB, in the blood. Troponin stays elevated for 1-2 weeks after myocardial infarction, while CK-MB stays elevated for 1 to 2 days after myocardial infarction. However, troponin tests are more popular than CK-MB tests in laboratories. So, this is the summary of the difference between troponin and CK-MB.
Reference:
1. Anthony, Kiara. “What You Need to Know about Troponin, an Important Protein.” Healthline.
2. “CPK-MB.” StatPearls – NCBI Bookshelf.
Image Courtesy:
1. “Conformational change of troponin” By Sheng JJ – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “AMI bloodtests engl” By J. Heuser JHeuser – self made modified from ACC/AHA Practice Guidelines 2005 p E32 – selbst gemacht abgewandelt von ACC/AHA Practice Guidelines S. E32 (CC BY-SA 3.0) via Commons Wikimedia