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Lab Dept:
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Coagulation
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Test Name:
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ACTIVATED PROTEIN C RESISTANCE
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General Information
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Lab Order Codes:
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APCRB
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Synonyms:
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APC resistance; APCR; Screen for Factor V Leiden
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CPT Codes:
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85307 – Activated Protein C (APC) resistance assay
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Test Includes:
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APCR ratio
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Logistics
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Test Indications:
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Useful for diagnosing patients who are predisposed to thrombosis and are not responding appropriately to anticoagulant therapy. Used as a screen to rule out the presence of Factor V Leiden.
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Lab Testing Sections:
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Coagulation (Minneapolis Campus)
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Phone Numbers:
Minneapolis:
Saint Paul:
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612-813-6280
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651-220-6550
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Test Availability:
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Monday – Friday (0630 – 1500)
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Turnaround Time:
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1 – 3 days
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Special Instructions:
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Test can be performed on patients on Coumadin and/or heparin. Test cannot be performed on patients on argatroban or like products.
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Specimen
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Specimen Type:
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Whole blood
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Container:
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Light Blue top (Buffered Na citrate 3.2%) tube
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Draw Volume:
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2.7 mL blood in a 3 mL tube (Minimum: 1.8 mL in a 2 mL tube)
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Processed Volume:
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Minimum 1.8 ml (plasma).
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Collection:
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A clean venipuncture is essential.
If the patients hematocrit is >55%, call the laboratory for a special tube. Fill tube completely.
Mix thoroughly by gentle inversion.
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Special Processing:
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Lab Staff: All testing will be performed in Minneapolis.
St.Paul Lab: Send whole blood specimens to Mpls. For processing via courier. Must be processed within 4 hours of collection. Contact Mpls. Prior to sending
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Patient Preparation:
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Patient should not be receiving argatroban or like products
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Sample Rejection:
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Improper tube; clotted sample; underfilled tube; mislabeled or unlabeled specimens
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Interpretive
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Reference Range:
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APC Ratio
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Interpretation
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<1.5
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Suggests Factor V Leiden is present
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1.5 - 2.0
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Borderline
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>2.0
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Unlikely Factor V mutation is present
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Clinical Interpretation: Functional clotting test for resistance to activated Protein C: Up to 90% of activated Protein C resistance is caused by Factor 5 Leiden mutation which can be detected using PCR molecular testing.
If APCR is positive (or borderline), Factor 5 Leiden is recommended
If APCR is positive and Factor 5 Leiden is negative, APCR is likely due to another mutation (10 – 15% of cases).
If APCR is negative, it is unlikely any Factor 5 mutation is present.
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Critical Values:
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N/A
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Limitations:
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Test cannot be performed on patients on argatroban or like products.
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Methodology:
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The Siemens Factor V Leiden Assay is based on the activation of endogenous Protein C by incubation of plasma with Agkistrodon contorix (Southern Copperhead) venom. A dilute Russells Viper Venom time (DRVVT) is then performed on the plasma. The DRVVT is sensitive to prolongation in the presence of APC.
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References:
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Factor V Leiden Assay (May 2005) Siemens Package Insert, Siemens Healthcare Diagnostics,Marburg Germany
Bertina RM, Koeleman BP,Koster T, et al (1994) Mutation in blood coagulation factor V associated with resistance to activated protein C. Nature; 369:64-67.
Dahlback B (1994) Physiological anticoagulation. Resistance to activated protein C and venous thrombo-embolism. J Clin Invest; 94 923-7.
Thrombophilia Powerpoint presentation Kandice Kottke-Marchant M.D. PhD. http://aniaracorp.s3.amazonaws.com/PhyFiles/Thrombophilia2/Marchant_medium.wmv
An Algorithmic Approach to Hemostasis Testing Kottke-Marchant (2008) CAP Press
ProC Control Plasma package insert (May 2008) Siemens Healthcare Daignostics, Marburg Germany
Application Sheet for Factor V Leiden Assay on the BCA and BCS XP System.
An Algorithmic Approach to Hemostasis Testing (2008) Kottke-Marchant, CAP Press
Control Plasma N package insert (December 2007) Siemens Healthcare Diagnostics, Newark, DE
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Updates:
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2/6/2012: Test moved from referral to Fairview University to being performed at inhouse at Children’s Laboratory.
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