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Lab Dept:
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Coagulation
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Test Name:
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ARIXTRA ASSAY
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General Information
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Lab Order Codes:
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ARIX
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Synonyms:
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Fondaparinux Assay
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CPT Codes:
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85520 – Heparin Assay
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Test Includes:
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Logistics
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Test Indications:
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Fondaparinux is a synthetic anticoagulant with selective inhibition of activated factor X (factor Xa). Fondaparinux induces a conformational change in antithrombin and increases its affinity for factor Xa. Inhibition of faxtor Xa leads to decreased thombin generation and thrombus development. Fondaparinux has a half-life of approximately 17 hours which allows once-daily dosing. It is almost completely excreted by the kidneys. Fondaparinux is approved for the prophylaxis and treatment of venous thromboembolic events. Laboratory monitoring of Fondaparinux is possible by utilizing factor Xa inhibitory activity of the drug. Anti-Xa assay (used for monitoring heparin) is modified by using a standard curve constructed with Fondaparinux.
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Lab Testing Sections:
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Chemistry - Sendouts
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Referred to:
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Fairview Diagnostic Laboratories (Fairview Code: ARIX)
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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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Daily, 24 hours
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Turnaround Time:
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4 – 8 hrs if received during lab hours; with pre-notification, stats are done within 1 hour
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Special Instructions:
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See Patient Preparation. Test must be performed (or processed and plasma frozen) within 3 hours of collection.
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Specimen
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Specimen Type:
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Blood
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Container:
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Blue Top Na Citrate, 3.2% - fill to fill line on tube.
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Draw Volume:
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2.7 mL (in 3 mL tube) – filled to fill line on tube.
(Minimum: 1.8 mL (in 2 mL tube) – filled to fill line on tube.
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Processed Volume:
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Lab Staff: If less than 3 hrs is required for transport, do not centrifuge. If more than 3 hrs is required for transport, centrifuge for 30 minutes, remove clear, lipid-free plasma, aliquot into 0.3-0.5 mL aliquots into separately labeled polypropylene tubes and immediately place on dry ice or in -70 degree Centigrade freezer.
Ship whole blood specimens at Room Temperature and processed plasma specimens on dry ice. Must arrive within 48 hours.
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Collection:
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Routine venipuncture. Deliver to the laboratory ASAP.
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Special Processing:
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Lab Staff: If less than 3 hours is required for transport, do not centrifuge. If more than 3 hours is required for transport, centrifuge for 30 minutes, remove clear, lipid-free plasma, aliquot into polypropylene tubes (3-4 with ~0.5 mL plasma in each tube), and immediately place on dry ice or in -70C freezer. Ship whole blood at room temperature.
Whole blood: Must arrive at reference lab within 3 hours of collection.
Plasma: Ship processed plasma specimens on dry ice. Must arrive within 48 hours of shipment.
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Patient Preparation:
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To measure peak plasma level, the sample should be collected 3 hours after drug administration.
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Sample Rejection:
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Underfilled tubes, overfilled tubes, mislabeled tubes, unlabeled tube, inappropriate processing or storage,
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Interpretive
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Reference Range:
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Prophylactic plasma level: 0.3-0.5 mg/L
Therapeutic plasma level: 0.8-1.20 mg/L
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Critical Values:
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N/A
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Limitations:
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N/A
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Methodology:
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Xa assay for Arixta
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References:
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Fairview Diagnostic Laboratories December 2012
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