Amylase.

The laboratory determination of serum and urine amylase activity is commonly requested by the Emergency physician. While depressed levels are occasionally seen, they are almost always secondary to chronic pancreatitis and pancreatic destruction. The typical abnormality is an elevation that may represent a normal physiologic process, a benign inflammation, the concomitance of ongoing disease, or an emergent problem. The differential diagnosis of hyperamylasemia is difficult, but most high levels are caused by pancreatitis and biliary tract disease. Serial determinations of amylase levels, as well as simultaneous assessments of urine and serum amylase, may be useful in determining the source of the problem. The laboratory methods for measurement are many and varied, reflecting the lack of a perfect test. Because of the different procedures, confusion has ensued over the units of description and the normal or reference ranges. Any standard equipped medical laboratory should be able to determine amylase activity in both serum and urine in a timely fashion. The average cost per amylase determination is $17.75. The actual time to perform the test in the laboratory is approximately 7.5 minutes, though turnaround times usually exceed 1 hour. The fractionation of amylase into isoenzymes is a sophisticated procedure requiring equipment not routinely found in a typical hospital laboratory.