Test ID: WRF
Warfarin, Serum
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Monitoring patients whose prothrombin time is inconsistent with the prescribed warfarin dose, particularly when failure to comply or surreptitious drug use is suspected.
Note: This test is not useful for evaluation of the patient with prolonged bleeding time suspected of exposure to rat poisons.
Method Name A short description of the method used to perform the test
High-Performance Liquid Chromatography (HPLC)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Coumadin
Oral Anticoagulants
Panwarfarin
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: Red top
Specimen Volume: 3 mL
Collection Instructions: Spin down within 2 hours of draw.
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.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | Mild OK; Gross reject |
| Icterus | Mild OK; Gross reject |
| Other | Serum gel tube |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum Red | Refrigerated (preferred) | 14 days |
| Ambient | 14 days | |
| Frozen | 14 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Warfarin (Coumadin) is an anticoagulant that acts by antagonizing the action of vitamin K resulting in the same coagulation abnormalities produced by vitamin K deficiency.
Warfarin reduces the levels of prothrombin and factors VII, IX, and X, thereby prolonging the prothrombin and partial thromboplastin times.
Warfarin produces its anticoagulant effect within 36 to 72 hours of initiating therapy, and the duration of action may persist for 4 to 5 days following withdrawal of drug.
Warfarin circulates almost completely bound to albumin (>98%), and its half-life ranges from 20 to 60 hours.
Abnormal bleeding is the chief complication of overdose.
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.
Therapeutic concentration: 2.0-5.0 mcg/mL
Toxic concentration: > or =10.0 mcg/mL
Interpretation Provides information to assist in interpretation of the test results
Therapeutic concentration: 2.0 to 5.0 mcg/mL
Toxic concentration: > or =10.0 mcg/mL
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test is not useful for evaluation of the patient with prolonged bleeding who are suspected of exposure to rat poisons.
Patients transfused with fresh-frozen plasma may have a disparity between their warfarin level (elevated) and a relatively normal prothrombin.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
Gallus A, Jackaman J, Tillett J, et al: Safety and efficacy of warfarin started early after submassive venous thrombosis or pulmonary embolism. Lancet 1986;2:1293-1296
Method Description Describes how the test is performed and provides a method-specific reference
Serum is extracted with petroleum ether. The extract is chromatographed and the distinctive peaks of the coumarins are identified and quantitated in the ultraviolet spectrum.(O'Reilly RA, Aggeler PM, Hoag MS, Leong L: Studies on the coumarin anticoagulant drugs: the assay of warfarin and its biologic application. Thromb Diath Haemorrh 1962;8:82-95; Fishwick FB, Taylor A: The determination of warfarin in animal relicta. Analyst 1967;92:192-195)
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.
Wednesday; 9:00 a.m.
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.
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.
80299
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 |
|---|---|---|
| 8760 | Warfarin, S | 4098-0 |
External
link
PDF
document
Excel
document
Word
document