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| Test Description |
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Test Name
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Factor IX Inhibitor Assay |
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Synonym(s)
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Factor IX Antibody Assay |
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Description
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The Factor IX inhibitor assay is used to detect and quantify anti-Factor IX antibodies in patients with Hemophilia B. This assay cannot be performed on patients with normal Factor IX activity levels. Samples drawn post infusion of Factor IX will reflect saturation of the inhibitor by the infused Factor IX. |
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Methodology
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Clotting |
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Performed
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Sunday-Saturday |
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Turnaround Time
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1-3 days |
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Specimen Requirements
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3 mL platelet-poor citrated plasma (light blue 3.2% sodium citrate tube). Freeze plasma within 4 hours of collection in 1 mL aliquots.
Transport frozen.
Minimum volume 2 mL.
Coagulation Drawing Instructions:
- When drawing coagulation tests, always draw a "pilot" tube (7-10 mL plain red top tube, completely filled). This removes tissue fluid contamination, discard pilot tube.
- Draw blood in a light blue (3.2% sodium citrate) top tube. Fill tubes as far as vacuum will fill and mix gently. Ratio of anticoagulant and blood must be maintained. Avoid slow flowing draws and traumatic venipunctures.
- Spin vacutainer – remove plasma avoiding platelet/buffy layer – spin plasma again – remove top portion of plasma and place 1 mL of PLATELET-POOR PLASMA in plastic tube. (Glass tube unacceptable)
- Double-centrifugation is critical for accurate results as platelet contamination may cause erroneous results.
- Plasma must be frozen within 4 hours of collection.
- CRITICAL WARNING: Specimen must remain frozen until testing. Submit separate aliquots when multiple tests are ordered on same patient specimen.
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Rejection Criteria
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Plasma hemolyzed, thawed or contaminated with heparin. |
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CPT Code(s)
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85335, 85250, 85390 |
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Reference Range
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See interpretive report. |
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Contact Information
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Hemostasis Lab: 214-645-5067
Customer Service: 214-645-7057, Toll Free 877-887-8136 |
Last Modified: 01/05/2011 |
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