Enzyme diagnostics make use of the fact that in inflammation of individual organs, certain enzymes that are otherwise absent in the blood pass into the blood. The longest known is the measurement of the activity of amylase in blood and urine for the detection of diseases of the pancreas. In prostate cancer, a specific (acid) phosphatase is increased in the blood, which is formed only in this organ, while various alkaline phosphatases are increased or decreased in diseases of the liver, kidney and bone. Other enzymes are increased in liver and muscle diseases as well as in myocardial infarction.
American research revealed differences between enzymes of the same function but of different origins (isoenzymes), which should provide insights into many diseases.