The term 'enzymes' refers to complex proteins that act as catalysts for chemical reactions that are essential for healthy functioning of the human body. Each enzyme acts only on a specific reactant or substrate, initiating or accelerating specific chemical reactions. Amylase is one such enzyme that plays a vital role in digestion. Its main function is to break down starches or complex carbohydrates. It is primarily synthesized by the salivary glands and the pancreas. Pancreatic and salivary amylase are placed in the category of alpha amylases. Salivary amylase (ptyalin) is responsible for the hydrolysis of starch into maltose and dextrin.
Amylase acts on dietary starch and converts it to simpler molecules like disaccharides and trisaccharides, which are then converted to glucose that is used by the body to release energy. Around 55% to 60% of the amylase found in the blood is secreted by the salivary glands, and the rest is secreted by the pancreas.
Normal Range for Amylase in Blood and Urine
Elevated levels of amylase could be indicative of certain medical conditions. Amylase levels can be checked by conducting serum amylase test and urinary amylase test. Decreased rate of clearance of amylase and/or increased rates of amylase entry into the bloodstream could lead to elevated serum amylase levels. Elevated concentration of amylase in urine and blood are often observed in people affected by acute pancreatic diseases. The following table provides the normal reference range for amylase in blood.
|Normal Amylase Levels|
|Age||Normal Range (units per liter)|
|Less than 60 years||25 - 125|
|60 years and above||24 - 151|
Amylase is found in very small amounts in urine in case of healthy individuals. If the serum amylase levels are normal, but symptoms are indicative of pancreatitis, doctors may recommend urine amylase test to get a clearer idea. For the test, a random urine sample or a 24-hour urine sample might be collected. Given below is the normal range for amylase in urine.
|Normal Range for Amylase in Urine|
|Urine Sample||Normal Range (nanokats/hour)|
|2-hour sample||16 - 283|
|24-hour sample||400 - 6,800|
It must be noted that the normal range may vary from lab to lab, depending on the method used for the test.
Causes of Hyperamylasemia
The term 'hyperamylasemia' refers to high levels of amylase enzyme in the blood. There are many different conditions that could lead to elevated amylase levels. These include:
Elevated amylase and lipase, along with certain symptoms like severe abdominal pain could be indicative of acute pancreatitis. Pancreatitis refers to the inflammation of the pancreas. It is categorized into acute and chronic pancreatitis. Acute pancreatitis is characterized by sudden onset of symptoms, whereas chronic pancreatitis develops over time. Amylase levels could be more than three times the usual level in the first 24 hours. However, one in ten patients suffering from acute pancreatitis tend to have normal serum amylase levels. Under such circumstances, further testing is required for a proper diagnosis. Amylase levels are slightly elevated in people affected by chronic pancreatitis, but are usually lower in comparison to the levels seen in people affected by acute pancreatitis.
The formation of pancreatic pseudocysts is often a complication of pancreatitis. Unlike true cysts that are lined with epithelial cells, pseudocysts are fluid-filled pockets that contain amylase and other pancreatic enzymes. These may also contain scarred tissue, inflamed cells, necrotic pancreatic tissues, and blood. These are usually benign and asymptomatic. However, symptoms may appear if the cyst is large.
Salivary Gland Disorders
Around 55% to 60% of amylase is secreted by the salivary glands, which is why, malfunctioning of the salivary gland in the event of trauma or inflammation could cause the amylase levels to fluctuate. Elevated serum amylase levels might be observed in people affected by acute parotitis, which refers to inflammation of parotid gland (large salivary gland which produces almost half of the saliva that is produced during the day). Amylase levels may rise in case of people affected by mumps, which is a viral infection characterized by swelling of one or more salivary glands.
Besides the salivary gland and pancreatic disorders, amylase levels could also rise due to the following conditions:
➞ The terms 'cholelithiasis' and 'choledocholithiasis' refer to the presence of hardened deposits in the gallbladder (gallstone) and the common bile duct respectively. Gallstones can even lead to cholecystitis (inflammation of the gallbladder), which may lead to gallbladder attacks. Amylase levels are likely to rise in people affected by these conditions.
➞ Elevated levels of amylase might be observed in people affected by macroamylasemia, which refers to the presence of macroamylase in the blood. Macroamylase consists of amylase attached to a protein. Due to its large size, filtration of macroamylase from blood by the kidneys takes longer.
➞ Peptic ulcers are characterized by sores in the lining of the stomach. Gastric acid may leak in case of a perforated ulcer, thereby causing inflammation of the pancreas. Amylase levels are likely to rise if the pancreas gets inflamed.
➞ Other conditions wherein the amylase levels may rise include ectopic pregnancy (implantation of the fertilized egg outside the uterus), severe gastroenteritis, peritonitis, bowel obstruction, diabetic ketoacidosis , blockage of bile duct, renal diseases, etc.
On a concluding note, amylase levels are usually monitored in cases where pancreatic damage is suspected. Lipase (enzyme that is secreted by the pancreas into the small intestine) levels may also be monitored for the same reason.
Disclaimer: The information provided in this article is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.