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Overview :
The diagnosis of acute pancreatitis can be difficult to make,
especially when mild, late in its course or when multiple other disorders are
present.
Testing: Amylase and lipase should be tested simultaneously.
Results for both may be expressed as multiples of the upper limit of normal.
lipase as multiple of upper limit of normal =
= (serum lipase in patient) / (upper limit of reference range
for lipase)
amylase as multiple of upper limit of normal =
= (serum amylase in patient) / (upper limit of reference
range for amylase)
Interpretation
Acute pancreatitis is highly likely if:
(1) The serum lipase is > 5 times the upper limit of
normal.
(2) Increases
then decreases in serum amylase and lipase are in concert.
(3) Serum lipase values show significant change over
time.
Elevations in amylase and lipase less than 3 times the upper
limit of normal can be seen in conditions other than pancreatitis, including
drug effect or acute abdomen with bowel infarction or perforation.
Very high elevations in amylase (greater than 25 times the
upper limit of normal) can be seen in metastatic cancers.
An increase in ALT to 3 or more times normal suggests
gallstone-induced pancreatitis.
Limitations:
• Amylase
by itself is relatively insensitive for making the diagnosis of pancreatitis. It
may be normal at presentation and tends to fall to normal more rapidly than
lipase, so that in late pancreatitis only the lipase is elevated.
• The
magnitude of increase in amylase levels may not correlate with severity of
underlying disease.
• Amylase
of salivary gland origin needs to be distinguished from amylase of pancreatic
origin.
• Many
drugs can cause mild increases in both amylase and lipase without evidence of
acute pancreatitis.
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