Amylase is an enzyme found in the human body, in saliva and in the juices formed by the pancreas. The function of amylase is to break starches into smaller molecules as part of the process of digestion. Amylase concentration is the amount of amylase present in a given volume of fluid. Doctors often find a high amylase concentration in the blood of people who have pancreatitis, a condition in which inflammation of the pancreas occurs. This high amylase concentration can change to a low one over time, as the pancreas becomes damaged and unable to produce amylase.
The effects of salivary amylase begin the body's process of digesting food. As food is chewed inside the mouth, the amylase from saliva starts to act on any starch that is present, breaking it down into smaller sugars. In the pancreas, special cells make amylase, which is then secreted in digestive juices. These leave the pancreas and enter the gut to act on food when it arrives there. While normal amylase concentrations in blood and urine suggest that the pancreas is working properly, levels that are abnormally low or high can indicate a problem.
Disorders known to affect blood amylase concentration include cancer of the pancreas and some kidney problems, as well as pancreatitis. Pancreatitis can be a sudden attack or a long-lasting illness, and symptoms include pain in the abdomen or back, fever, nausea and a reduced appetite. A kidney disease can lead to a higher than normal blood amylase concentration, if it prevents the kidneys from producing urine normally. As amylase is removed from the body in urine, kidney disease can cause the rate of amylase removal to fall, and blood amylase levels rise as a result. The amylase concentration in blood is sometimes used to check that pancreatic cancer treatments are working, as levels should return to normal if therapy is successful.
Experiments have been carried out using amylase and starch to find out how amylase concentration affects the rate of starch breakdown. It has been found that, as the concentration of amylase increases, so does the rate of starch digestion, until the amylase concentration reaches a certain point. This represents the point at which there are enough enzymes present to attach to all of the starch molecules, making it impossible for the breakdown to proceed any faster. Students in schools are sometimes taught simple experiments where they can test this for themselves.