Clinics and Departments

Laboratory Services

Lab Dept:

Coagulation

Test Name:

ACTIVATED PROTEIN C RESISTANCE

General Information

Lab Order Codes:

APCRB

Synonyms:

APC resistance; APCR; Screen for Factor V Leiden

CPT Codes:

85307 – Activated Protein C (APC) resistance assay

Test Includes:

APCR ratio

Logistics

Test Indications:

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.

Lab Testing Sections:

Coagulation (Minneapolis Campus)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Monday – Friday (0630 – 1500)

Turnaround Time:

1 – 3 days

Special Instructions:

Test can be performed on patients on Coumadin and/or heparin. Test cannot be performed on patients on argatroban or like products.

Specimen

Specimen Type:

Whole blood

Container:

Light Blue top (Buffered Na citrate 3.2%) tube

Draw Volume:

2.7 mL blood in a 3 mL tube (Minimum: 1.8 mL in a 2 mL tube)

Processed Volume:

Minimum 1.8 ml (plasma).

Collection:

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.

Special Processing:

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. If there will be a delay in delivery, the sample
should be spun, plasma removed and spun again. Aliquot spun plasma into a screw-capped plastic vial and freeze at -70. Send frozen plasma.

Patient Preparation:

Patient should not be receiving argatroban or like products

Sample Rejection:

Improper tube; clotted sample; underfilled tube; mislabeled or unlabeled specimens

Interpretive

Reference Range:

APC Ratio

Interpretation

<1.5

Suggests Factor V Leiden is present

1.5 - 2.0

Borderline

>2.0

Unlikely Factor V mutation is present

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.

Critical Values:

N/A

Limitations:

Test cannot be performed on patients on argatroban or like products.

Methodology:

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.

References:

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

Updates:

2/6/2012: Test moved from referral to Fairview University to being performed at inhouse at Children’s Laboratory.



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