Amylase, Timed Collection, Urine
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Assessment of acute rejection of bladder-drained pancreas transplants
As an aid in the diagnosis of acute pancreatitis
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Amylase, Timed Collection, U
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube: Plastic, 6-mL tube (Supply T465)
Specimen Volume: 5 mL
1. Collect a 2-hour urine specimen.
2. The patient should have nothing by mouth except water between the hours of 6 p.m. and 10 a.m.
3. The bladder should be completely emptied at 8 a.m. This urine is discarded.
4. An adequate urine specimen (>100 mL) is ensured if the patient drinks 3 or more 8-ounce glasses of water. Half of this amount should be ingested between 7:30 a.m. and 8 a.m. The second half should be ingested at 8:30 a.m.
5. Collect all urine after 8 a.m. in container supplied.
6. The collection ends at 10 a.m. Include the 10 a.m. void in the collection container.
7. Measure and record the 2-hour volume.
8. Overlay urine with toluene (5 mL), and send aliquot. If no toluene is available, refrigerate specimen during collection, and send the aliquot specimen frozen.
9. Record the date and time (the exact start and completion times of the 2-hour collection) on the container label.
Additional Information: For any timed collection the volume and length of collection is required.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
|Urine||Refrigerated (preferred)||7 days|
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Amylases are enzymes that hydrolyze complex carbohydrates. They are produced by a number of organs and tissues, predominantly the exocrine pancreas (P-type amylase) and salivary glands (S-type amylase). Plasma amylases are of relatively low molecular weight for an enzyme (55,000-60,000 daltons) and enter the urine through glomerular filtration. Conditions that cause increased entry of amylase into plasma (eg, acute pancreatitis) will thus result in increased urinary excretion of amylase. Therefore, urinary amylase is sometimes used in the diagnosis of acute pancreatitis. However, the rate of urinary amylase excretion appears to be less sensitive than plasma markers, and is not specific for the diagnosis of acute pancreatitis.
Similar to other low-molecular-weight proteins filtered by glomeruli, amylases are reabsorbed to an extent by the proximal tubule. Thus, conditions associated with increased production and glomerular filtration of other low-molecular-weight proteins that compete with tubular reabsorption of amylase or conditions of proximal tubular injury may increase urinary amylase excretion. Also, a number of disorders other than acute pancreatitis may cause increases in plasma 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.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
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.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
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
Method Description Describes how the test is performed and provides a method-specific reference
This is an enzymatic rate reaction. The liquid Roche amylase method is an enzymatic colorimetric test using 4,6-ethylidene (G7)-p-nitrophenol (G1)-a, D-maltoheptaoside (ethylidene-G7PNP) as a substrate. Human salivary and pancreatic amylase convert the substrate at approximately the same rate. The alpha-amylase cleaves the substrate into G2, G3, G4 PNP fragments. The G2, G3 and G4 PNP fragments are further hydrolyzed by an alpha-glucosidase to yield p-nitrophenol and glucose. The rate of increase in absorbance at 415 nm (measuring the increase in p-nitrophenol) is proportional to amylase activity. (Package Insert: Roche P-Amylase, Roche Diagnostic Corp., Indianapolis, IN)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Sunday; Continuously
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
|Result ID||Reporting Name||LOINC Code|
|AMY_U||Amylase, Timed Collection, U||1799-6|