Amylase

The blood amylase test is used to help diagnose and monitor acute pancreatitis. It may also be used to diagnose and monitor chronic pancreatitis and other disorders that may involve the pancreas.

The blood amylase test may be used along with a lipase test to detect pancreatic diseases. While the amylase test is sensitive for pancreatic diseases, it is not specific. That means an elevated amylase level may indicate a problem, but the cause may not be related to the pancreas. The lipase test, on the other hand, is more specific than amylase for diseases of the pancreas, particularly for acute pancreatitis and for acute alcoholic pancreatitis. An elevated lipase usually indicates a problem with the pancreas. Evaluating the results of the two tests together helps to diagnose or rule out pancreatitis and other conditions.

A urine amylase test may also be used to detect pancreatic diseases. Typically, its level will mirror blood amylase concentrations, but both the rise and fall will occur later. Sometimes a urine creatinine level may be ordered along with the urine amylase. The ratio of amylase to creatinine can be calculated and used to assess kidney function. Kidney dysfunction can result in a slower rate of amylase clearance.

In certain cases, for example when there is an accumulation of fluid in the abdomen (ascites), an amylase test may be performed on peritoneal fluid to help make a diagnosis of pancreatitis.

Amylase tests are sometimes used to monitor treatment of pancreatic cancer and after the removal of gallstones that have caused gallbladder attacks.

A blood amylase test may be ordered when a person has signs or symptoms of a pancreatic disorder, such as:

• Severe upper abdominal pain that radiates to the back or feels worse after eating
• Fever
• Loss of appetite
• Nausea, vomiting
• Yellowing of the eyes or skin (jaundice)
• Rapid pulse
• Loose, fatty, foul-smelling stools (steatorrhea)

A urine amylase test may be ordered along with or following a blood amylase test. One or both may also be ordered periodically when a healthcare practitioner wants to monitor a person to evaluate the effectiveness of treatment and to determine whether amylase levels are increasing or decreasing over time.

A high amylase level in the blood may indicate the presence of a condition affecting the pancreas.

In acute pancreatitis, amylase in the blood often increases to 4 to 6 times higher than the highest reference value, sometimes called the upper limit of normal. The increase occurs within 4 to 8 hours of injury to the pancreas and generally remains elevated until the cause is successfully treated. The amylase values will then return to normal in a few days.

Amylase and lipase results may be interpreted together. In acute pancreatitis, lipase levels usually rise in about the same time as blood amylase levels, about 3-6 hours, but lipase levels will remain elevated longer than amylase levels. Lipase testing is thought to be more reliable than amylase testing for the initial diagnosis of acute pancreatitis and is also more sensitive to detecting acute pancreatitis caused by acute alcoholic pancreatitis.

In chronic pancreatitis, amylase levels initially will be moderately elevated but often decrease over time with progressive pancreas damage. In this case, levels returning to normal may not mean that the source of damage has been resolved. The magnitude of increase in amylase level does not indicate severity of pancreatic disease.

Amylase levels may also be significantly increased in people with pancreatic duct obstruction and pancreatic cancers.

In general, urine amylase levels rise in proportion to blood amylase levels and will stay elevated for several days after blood levels have returned to normal.

An increased level of amylase in peritoneal fluid can occur in acute pancreatitis but may also occur in other abdominal disorders, such as obstructed intestine or decreased blood flow to the intestines (infarct).

A low amylase level in blood and urine in a person with pancreatitis symptoms may indicate permanent damage to the amylase-producing cells in the pancreas. Decreased levels can also be due to kidney disease and pre-eclampsia.

Increased blood amylase levels with normal to low urine amylase levels may indicate the presence of a macroamylase, a benign complex of amylase and other proteins that accumulates in the blood.

Since the salivary glands also produce amylase, conditions such as mumps and obstructed salivary glands can also cause increased blood levels of amylase.

Chronic pancreatitis is often associated with alcoholism. It may also be caused by trauma or pancreatic duct obstruction or may be seen in association with genetic abnormalities such as cystic fibrosis.

In addition to the pancreas and salivary glands, amylase is produced in other parts of the body, such as the small intestine, ovaries, fallopian tubes and liver. However, most laboratory tests simply measure total amylase in the blood based on the fact that most of the amylase in blood, urine and fluids comes from the pancreas.

No. Amylase levels may also be significantly increased in people with gallbladder attacks. Urine and blood amylase levels may be moderately elevated with a variety of other conditions, such as ovarian cancer, lung cancer, tubal pregnancy, acute appendicitis, diabetic ketoacidosis, mumps, intestinal obstruction, or perforated ulcer, but amylase tests are not generally used to diagnose or monitor these disorders.