Creatine kinase is a crucial enzyme to our very existence. This is an enzyme that catalyses a very crucial reaction in energy conversion in the muscles. Note that apart from the muscles that we are familiar with like the ones in the arms and legs, the heart and chest muscles also exist and anything that affects muscles can have a serious repercussion on our very existence. To understand creatine kinase’s role in disease, it is important to understand creatine and the role that it plays.
The entire process starts with ATP and ADP. In the mitochondria of every cell, energy is created by the conversion of ATP (adenosine triphosphate) to adenosine diphosphate (ADP). With this reaction, one molecule of phosphorus is released along with energy as well, which we use in order to move. The body then has to convert this ADP back to ATP so that the action can be repeated, but this requires energy. This energy that is required comes from the burning of carbohydrates and fats. However, this is a lengthy procedure and if this was the only mechanism, we would tire out faster and have to wait before performing the next task.
This is where creatine, created in the kidneys, comes in. When ATP is burnt in the presence of creatine, it creates ADP and phosphocreatine. This occurs because of the creatine kinase enzyme. Phosphocreatine can then be converted back to ATP in a reversible reaction with another creatine kinase variant. What this means is that creatine becomes a capacitor by storing energy in one form and rapidly transferring it back. This is what allows for continuous energy. Creatine kinase should ideally only exist in the muscles and serum where it is transported to the required cells; however, there is a limit for this set between 24 and 320 units. If this is elevated, it means that creatine kinase is leaking out of muscles.
This means that the muscles are degrading and can indicate cardiac muscle damage or myopathy. It can also be an indication of muscle wasting in muscular dystrophy and some forms of genetically acquired diseases like Duchenne-Becker muscular dystrophy. To specifically isolate the heart as the problem point, an additional troponin test is also conducted. It is noteworthy that even the brain uses creatine kinase but of a different variety. This is called creatine kinase –B (brain) and the muscular creatine kinase is also called creatine kinase –M (muscular).