Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

AMS
8352
amylase concentrations and consequent increases in urinary amylase excretion. These conditions include
burns, ketoacidosis, myeloma, light-chain proteinuria, march hemoglobinuria, acute appendicitis,
intestinal perforation, and following extracorporeal circulation. Quantitation of urinary amylase excretion
is also useful in monitoring for rejection following pancreas transplantation. The duodenal cuffs of donor
pancreases are often surgically anastomosed to the recipient's bladder at the time of pancreas
transplantation, allowing for drainage of exocrine pancreas fluid into the bladder. In pancreatic rejection,
urinary amylase excretion decreases.
Useful For: Assessment of acute rejection of bladder-drained pancreas transplants As an aid in the
diagnosis of acute pancreatitis
Interpretation: Decreases in urinary amylase excretion of greater than 30% to 50%, relative to
baseline values, may be associated with acute pancreas allograft rejection. Because there is large
day-to-day variability in urinary amylase excretion following pancreas transplantation, if a significant
decrease is noted, it should be confirmed by a second collection. There is also large inter-individual
variability in urinary amylase excretion among pancreas transplant recipients. Collecting a timed urine
specimen and expressing the urinary amylase level as Units excreted/hour might reduce variability and
improve test performance. However, acute rejection is usually not established solely by changes in
urinary amylase excretion, but by tissue biopsy. Urinary amylase is elevated in acute pancreatitis, but
the test has poor sensitivity and specificity.
Reference Values:
3-26 U/hour
Clinical References: 1. Tietz Textbook of Clinical Chemistry. 3rd edition. Edited by CA Burtis,
ER Ashwood. Philadelphia, WB Saunders Co., 1999, pp 689-698 2. Munn SR, Engen DE, Barr D, et al:
Differential diagnosis of hypo-amylasuria in pancreas allograft recipients with urinary exocrine
drainage. Transplantation 1990;49:359-362 3. Klassen DK, Hoen-Saric EW, Weir MR, et al: Isolated
pancreas rejection in combined kidney pancreas transplantation. Transplantation 1996;61:974-977 4.
Benedetti E, Najaran JS, Gruessener AC, et al: Correlation between cystoscopic biopsy results and
hypoamylasuria in bladder-drained pancreas transplants. Surgery 1995;118:864-872
Amylase, Total, Serum
Clinical Information: Amylases are a group of hydrolases that degrade complex carbohydrates into
fragments. Amylase is produced primarily by the exocrine pancreas where the enzyme is synthesized by
the acinar cells and then secreted into the intestinal tract by way of the pancreatic duct system.
Amylases also are produced by the salivary glands, small intestine mucosa, ovaries, placenta, liver, and
fallopian tubes. Pancreatic and salivary isoenzymes are found in serum.
Useful For: Diagnosis and management of pancreatitis Evaluation of pancreatic function
Interpretation: In acute pancreatitis, a transient rise in serum amylase activity occurs within 2-12
hours of onset; levels return to normal by the third or fourth day. A 4-6 fold elevation of amylase
activity above the reference limit is usual with the maximal levels obtained in 12-72 hours. However, a
significant number of subjects show lesser elevations and sometimes none. The magnitude of the
elevation of serum enzyme activity is not related to the severity of pancreatic involvement.
Normalization is not necessarily a sign of resolution. In acute pancreatitis associated with
hyperlipidemia, serum amylase activity may be spuriously normal; the amylasemia may be unmasked
either by serial dilution of the serum or ultracentrifugation. A significant amount of serum amylase is
excreted in the urine, and therefore, elevation of serum activity is reflected in the rise of urinary amylase
activity. Urine amylase, as compared to serum amylase, appears to be more frequently elevated, reaches
higher levels and persists for longer periods. However, the receiver operator curves (ROC) of various
serum and urine amylase assays demonstrated that all urine assays had poorer diagnostic utility than all
serum assays. In quiescent chronic pancreatitis, both serum and urine activities are usually subnormal.
Because it is produced by several organs, amylase is not a specific indicator of pancreatic function.
Elevated levels also may be seen in a number of non-pancreatic disease processes including mumps,
salivary duct obstruction, ectopic pregnancy, and intestinal obstruction/ infarction.
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