Amylase isoenzymes

Amylase isoenzymes

Clinical significance

Amylase is a hydrolase that catalyzes the hydrolysis of the 1,4-glycosidic bonds of glycogen and starch. It is produced and stored primarily in the salivary glands and pancreas, with smaller amounts in the lungs, thyroid, intestines, and in the mucusówomb and fallopian tubes. It is secreted into the gastrointestinal tract and circulation. Due to its low molecular weight, it is excreted in the urine. An increase in activity both in serum and urine occurs in acute pancreatitis and is at least 10-20 times above normal values in serum. Increasing values occur 6-12 hours after the onset of disease symptoms, maximum levels are after about 24 hours, and the decrease in activity is after 2-3 days. Amylase is also elevated in disorders of salivary secretion (salivary gland inflammation, salivary duct stones and others). To a lesser extent, amylase activity is increased in intestinal obstruction, gastric ulcer perforation, folliculitis, appendicitis, peritonitis, ketoacidosis in diabetes, ethanol intoxication in alcoholicsów, pancreatic cancer. Chronic pancreatitis can occur with a normal or slight increase in activity.Two isoenzymes are known: pancreatic P - increases in circulation in inflammation of the pancreas and salivary S - increases in diseases of the salivary glands, parotitis (mumps), as well as in others, e.g. inflammatory conditions, lung cancer. Salivary isoenzyme, due to its lower isoelectric point, is more difficult to filter in the kidney and is not detected in the urine. About 1% of healthy people have macroamylaseemia. Amylase forms a complex with immunoglobulin A or, less commonly, an "iatrogenic" complex after administration of high-molecular-weight compounds (glycoproteins, polysaccharides). In routine diagnosis, high serum amylase activity is detected, which may suggest acute pancreatitis. For ró¿nition, the ratio of amylase and creatinine clearance is calculated: (urine amylase/serum amylase) / (serum creatinine concentration/urine creatinine concentration) x 100%. Normally it is 1-4%, in macroamylase less than 1% (macroamylase due to its particle size is not excreted in the urine), in acute pancreatitis 7-10%.

Patient preparation

no special requirements

Material: Serum

Interventions

hemolysis, lipemia, dysproteinemias