Clinical Significance Of Enzymes
The measurement of enzymes level in serum is applied in diagnostic application. Detection of certain enzymes in the serum indicates that tissue or cellular damage has occurred resulting in the release of intracellular components into the blood. Hence, when a physician indicates that he/she is going to assay for liver enzymes, the purpose is to ascertain the potential for liver cell damage. Commonly assayed enzymes are the amino transferases: alanine transaminase, ALT (sometimes still referred to as serum glutamate-pyruvate aminotransferase, SGPT) and aspartate aminotransferase, AST (also referred to as serum glutamateoxaloacetate aminotransferase, SGOT); lactate dehydrogenase, LDH; creatine kinase, CK (also called creatine phosphokinase, CPK); gamma-glutamyl transpeptidase, GGT. Other enzymes are assayed under a variety of different clinical situations but they will not be covered here.
Pancreatic Enzymes
Acute pancreatitis is an inflammatory process where auto digestion of gland was noticed with activation of the certain pancreatic enzymes. Enzymes which involves in pancreatic destruction includes a-amylase, lipase etc.,
a-amylase
a-amylase (AMYs) are calcium dependent hydrolyase class of metaloenzyme that catalyzes the hydrolysis of 1, 4- a-glycosidic linkages in polysaccharides. Molecular weights of AMYs are human plasma ranges from 54 to 62 kDa. Due to its smaller size they could easily pass the glomeruli of the kidneys and AMY is the only plasma enzyme physiologically found in urine. The normal values of amylase is in range of 28-100 U/L. Marked increase of 5 to 10 times the upper reference limit (URL) in AMYs activity indicates acute pancreatitis and severe glomerular impairment. Pancreatic pseudocyst occurs if the plasma level of amylase activity fails to fall after an attack of acute pancreatitis.
Lipase
Lipase is single chain glycoprotein of molecular weight 48 kDa. Bile salts and a cofactor called colipase are required for full catalytic activity of lipase. Colipase is secreted by pancreas. Lipase is small molecule filtered through the glomerulus and totally reabsorbed by the renal tubules. Lipase is not normally detected in urine samples. The normal value of lipase ranges from 40-200 U/ L. Increase in plasma lipase activity indicates acute pancreatitis and carcinoma of the pancreas. So determination of both amylase and lipase together helps in the diagnosis of acute pancreatitis.
