Biomarkers are cellular, biochemical or molecular alterations that are measurable in biological media such as human tissues, cells, or fluids (Hulka et al, 1990). Enzymes, cell signalling molecules and proteins are examples of biomarkers. The main use of biomarkers is that of a diagnostic sense. They can indicate a variety of health or disease characteristics. Due to this they have become more prevalent in modern medicine when identifying and diagnosing patients with diseases. One of the main diseases that is diagnosed through the use of biomarkers is cardiovascular disease.
There are two categories of biomarkers: ones of exposure and those of diagnosis and monitoring disease. For biomarkers to be appropriate for checking for particular diseases they have to have certain characteristics. An ideal marker should be safe and easy to measure, cost efficient to follow up, modifiable with treatment and consistent across genders and ethnic groups (Mandal A, 2018). Different diseases have different biomarkers, this is as biomarkers are specific for a disease (Tandon R, 2016). Biomarkers have the ability to classify a population based on a genotype which is associated with a disease, thus allowing for the disease risk of a population to be verified (Mayeux R, 2004).
Cardiovascular disease (CVD) is the most prominent cause of death around the world. Traditional risk factors such as age, hypertension, diabetes mellitus and smoking have slightly improved the primary prevention of CVD (Haung Y et al, 2017). However, more recently biomarkers have been identified that are associated with CVD that could further help with prevention and lowering the mortality rate. When the heart has been under severe stress, from oxygen deprivation, cardiac biomarkers appear in the blood. This is due to proteins from heart muscle cells having leaked into the blood stream. The amount at which the biomarkers appear can point to the size of a heart attack and how seriously the heart has been affected. The cardiac biomarkers that are used to diagnose a heart attack are Cardiac troponin, Creatine Kinase (CK), CK-MB and Myoglobin (https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=cardiac_biomarkers). During a heart attack muscles of the heart are damaged. When the heart muscles are damaged cardiac troponin is released. The more cardiac muscle that is damaged the more troponin is released. So by measuring the amount of troponin in the blood you can tell how much damage there is to the heart muscles and thus the severity of the heart attack (https://medlineplus.gov/ency/article/007452.htm). CK is an enzyme which reversibly catalyses the phosphorylation of creatine by ATP, through the change of ADP to ATP. CK is released into the blood around 4 hours after heart cell damage occurs, and peaks around the 24 hour mark. A variant of CK is CK-MB; it is mainly found in the heart, but small amounts can be found in skeletal muscle. Levels of CK-MB may rise within 4 hours of having a heart attack but within a day they are usually back down to normal levels. This means they aren’t very helpful when trying to figure out whether a patient has had a heart attack in the last few days. However, more recently the use of CK as a diagnostic tool has been replaced in favour of using the more cardiac-specific non-enzymatic markers: Cardiac troponin (https://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/8336) . This is as CK levels can sometimes occur due to damage to other kinds of cells, as CK is present in various other non-cardiac muscle cells. Heart attacks can also be tested for by using the levels of myoglobin in the blood and urine. Myoglobin is found in heart and skeletal muscles, which is where it captures oxygen for muscle cells. Its fast acting and blood levels rise almost immediately after damage has occurred. Due to this myoglobin levels are able to identify acute myocardial infarctions, even if patients have normal cardiac troponin levels (Sallach SM et al, 2004). However, increased myoglobin levels don’t always mean a patient has suffered from a heart attack. High myoglobin levels can also point to myositis or muscular diseases such as muscular dystrophy (https://labtestsonline.org/tests/myoglobin). So it is widely common to do a variety of biomarker tests in order to determine whether a heart attack has taken place. The most trusted component of all the tests is usually an increased level in Cardiac troponin (https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=cardiac_biomarkers).Biomarkers might be useful tools in aiding the identification of diseases such as CVD, but they do have flaws. Variability between patients normal levels of biomarkers such as CK may cause confusion when testing is taking place (Mayeux R, 2004).
Despite this research into advances in biomarkers is thriving, in the hope that it can decrease the fatality rate connected with CVD. The main aim is to identify additional biomarkers, then those already known, by using new biological pathways. Through the use of clinical settings and using relatively new technologies such as the profiling of DNA, RNA and proteins of clinical specimens, it is hoped that new biomarkers will be discovered (May A, 2008).

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