Laboratory tests that measure enzyme levels and enzyme activity are known as enzyme assays. There are many types of measurement methods that measure the rate of enzyme activities and enzyme inhibitions. Enzymes are molecules that manipulate other molecules, known as substrates, by binding with them and chemically reacting with them to produce multiple by-products. The tests that measure this activity are for differing purposes, according to particular disease symptoms, and regard differing steps in enzymatic processes.
Assays that examine enzyme kinetics show how much more or less from the norm an enzyme behavior actually is. There are factors to control when taking enzyme assays, such as, enzymes work a specific way according to temperatures within an organism, and enzymes cannot tolerate high salt levels as too much salt interferes with an enzyme’s ability to bind with other proteins. Many enzymes can only operate within a small range of pH; therefore pH values in the body need to be measured as well. A high pH can inhibit enzyme activities completely.
There are two main types of enzyme assays: continuous, wherein constant readings are taken, and discontinuous, wherein after a period of time a chemical reaction is disturbed and the amount of substrate and by-products' concentrations are measured. In continuous assays, to test for levels of a substrate called NADH, which affects metabolism, or of NADPH, which affects a body’s ability to react well with drug therapies, a spectrophotometric assay is used, as they show up under its ultraviolet (UV) rays. What are called fluorometric assays define differences in fluorescence in some enzyme substrates. Calorimetric assays measure the amount of heat during enzyme chemical reactions and chemiluminescent assays measure the light produced during chemical reactions and can detect antibodies for diseases. In discontinuous assays, radiometric tests can measure absorption or release of radioactivity when proteins and substrate bind and chromatographic assays measure the formation of by-products of enzyme-substrate bindings.
Some blood tests are often run to test for particular enzyme levels to determine heart damages. There a certain number of several proteins that will be present in the blood in higher volumes when a heart muscle becomes damaged, for example. These tests must be carefully performed as kidney disease can also lead to nearly the same levels of these same enzymes. Another condition known as malignant hypertension can lead to elevated cardiac enzyme levels; therefore, tests other than enzyme assays will be necessary to determine the probable cause of the high enzyme levels.