Enzyme is a protein molecule that catalyzes the chemical reaction of other substances without itself being destroyed or altered upon completion of the reaction. Enzymes are a necessity for survival because without them, the chemical reactions would cease as enzymes speed up these reactions many folds. Enzymes can either be involved in production or destruction of a specific product e.g. the enzyme carbonic anhydrase has dual function: 1st it forms carbonic acid from carbon dioxide and water but later it decomposes this very acid to produce the hydrogen ion and bicarbonate ion as shown:
CO2 + H2O → H2CO3
H2CO3 → H+ + HCO3–
The formation of these enzymes is governed by the translation of genes encoded in a species DNA. Genetic abnormalities are therefore related to absence or abnormalities of enzymes themselves. So patients showing absence of enzymes mostly suffer from some genetic disease or syndrome. On the contrary, enzyme levels in the body may rise as well in response or as a consequence of some disorder or as an indicative of a disease to occur.
The enzyme, creatine phosphokinase, CPK provides muscles with rapid energy by the conversion of creatine to phosphocreatine. It does this especially in the skeletal muscles but also in the brain and smooth muscles such as those lining the blood vessel walls. So it is stored in the muscles of skeleton and the heart muscles as a reservoir of energy. CPK, in other words, is indicative of the muscle and cardiac activity so its levels may indicate abnormal muscle activities.
Most of the detectable enzymes in blood come from the various tissues and organs of the body. Abnormal values may indicate a problem with a specific organ. The most common blood enzyme tests are for liver and heart enzymes. It reflects the fact that when a tissue is damages, the enzymes stored within their cells are released into the surrounding fluid, which is the blood. So the level of injury to a vital organ may be reflected by the enzymes level in the surrounding blood.
Liver, the largest organ of the body and contributing to about 2% of the total body weight, is predominantly made up of hepatocytes. These hepatocytes are re-cycled throughout the life; however their rate of reformation being quicker than their rate of degeneration. However increased levels of alkaline phoaphatase, alanine transaminase and aspartate transamine are associated with liver problems. Alkaline phoshatase is a hydrolytic enzyme responsible for removing phosphate group from molecules. Its high levels indicate that the bile ducts are blocked, but its levels are high in children and pregnant women regardless of this. Alanine transaminase transfers an amino group from alanine to a-ketoglutarate. Its high levels in blood indicate alcoholic or viral hepatitis, CCF, liver damage, or biliary duct problems. However its levels fluctuate over the course of the day and even during strenuous activity. Aspartate transamine facilitates the conversion of aspartate and a-ketoglutarate to oxaloacetate and glutamate. It is raised in acute liver damage, damage to RBCs, cardiac muscle, skeletal muscle, kidney and brain tissue. It is measured clinically to determine the liver health. It is not only the liver whereupon an injury, enzymes are released in the blood, damage to other vital organs including heart, lungs, kidneys, brain and others also has the same consequence.
Therefore, the level of enzymes in blood provides crucial information about the health of an organ. Specified blood tests designated for these organs help in guessing the possible problem related to that organ and by doing so, early treatment for that ailment may be sought and patient be recovered as soon as possible.