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) Both serum amylase and lipase show increases then decreases 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.
