General (top of page)
Structure and Function: Amylase is an enzyme produced by the
exocrine glands with ability to cleave 1,4-glucose linkages. Amylase breaks down starch
into maltose and limit dextrans. Alpha-amylase is found in animals, beta-amylase in
plants. The enzyme requires calcium and chloride ions for activity. There are at least 2
amylase isoenzymes, S (salivary, 1) and P (pancreatic, 2). It is a lyase
(1,4-glucanglucanohydrolase). The molecular weight is 45,000 and the Enzyme Commission
number is EC 22.214.171.124.
Indications for testing
Measurement of serum amylase is currently rarely indicated as serum lipase has higher sensitivity and specificity for pancreatitis than serum amylase.
Elevated amylase concentrations in plasma (top of page)
High levels of serum amylase may be found in:
Amylase isoenzymes (top of page)
Amylase is usually measured in plasma as a test for pancreatitis. Occasionally there may be confusion over the tissue origin of a raised serum amylase when salivary gland or fallopian tubes may be implicated. Usually the simplest way to determine the likely source is to measure a serum lipase, as this enzyme is not found in the latter two structures. If necessary the pancreatic levels can be determined by immune-precipitation using a monoclinal antibody directed against salivary amylase. As each this test may take a week before a result is available, lipase is clearly a more useful test in most cases.
Amylase may be bound to an immunoglobulin to form macroamylase. While there is no clinical significance to the finding of a macroamylase in a patients plasma, it may cause some diagnostic dilemmas. A persistent elevated amylase with normal plasma lipase and no other features suggestive of pancreatic, salivary or abdominal disease is suggestive of macroamylasaemia. The diagnosis is supported by finding a normal level of plasma lipase and can be confirmed by finding a normal level of urinary amylase.
For details of SydPath Amylase assay see SydPath Test Database
For further information please contact Dr Graham Jones on 8382-9100
Last updated 21/01/2020