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Lab Dept:
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Coagulation
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Test Name:
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BETHESDA FVIII OTHER F8 CONCENTRATE
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General Information
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Lab Order Codes:
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BOTHR
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Synonyms:
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F8 Inhibitor Other Concentrate; Factor 8 Inhibitor Other Concentrate; Bethesda Factor 8 Other Concentrate, Bethesda Factor VIII Other Concentrate
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CPT Codes:
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85335 – Factor inhibitor test
85325 – Heparin neutralization (if applicable)
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Test Includes:
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Bethesda Assay, PTT inhibitor/inactivator assay, possibly heparin neutralizaton by hepzyme if necessary at an additional charge.
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Logistics
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Test Indications:
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The assay is designed specifically to measure the concentration of anti-Factor 8 antibodies in patients with hemophilia A. One Bethesda Unit is the amount of antibody that will inactivate 0.5 U/mL (50%) of Factor 8. Patients with spontaneous (acquired) antibodies will give variable results because of the unique conditions of the test and the nature of these types of antibodies.
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Lab Testing Section:
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Coagulation - Sendouts
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Referred to:
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Fairview University Medical Center (Fairview Test#: BETH3)
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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. Performed as needed.
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Turnaround Time:
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Results are reported within 2 - 4 days.
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Special Instructions:
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Indicate the other factor concentrate source. Also indicate on request form when the last factor VIII concentrate or cryoprecipitate was administered. No Heparin can be present in the specimen. If the thrombin time is long, hepzyme is added to determine if heparin is present in the sample.
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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 tube (Buffered Na Citrate 3.2%)
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Draw Volume:
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Three 3 mL tubes, each containing 2.7 mL blood (8.1 mL). (Minimum volume: Three-3 mL tubes, each containing 2.7 mL blood)
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Processed Volume:
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Specimen will be processed at the reference lab facility.
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Collection:
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Routine venipuncture. Do Not use the first 2 mL’s of blood collected. For correct anticoagulant to blood ratio, place 2.7 mL’s of blood in a 3 mL tube or 4.5 mL’s of blood in 5 mL tube.
If the patient’s hematocrit is >55%, contact laboratory to obtain a special tube. If the patient’s hematocrit is greater than 55%, contact laboratory to obtain a special tube. Mix thoroughly by gentle inversion.
If the patient has a coagulation abnormality, apply direct pressure tot the puncture site for 10 minutes; apply a pressure dressing. Instruct the patient to leave the bandage on for 12 hours.
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Special Processing:
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Lab Staff: Do Not process. If more than 24 hours is required for transport, contact laboratory for processing instructions. Ship at room temperature. The specimen must arrive within 24 hours.
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Patient Preparation:
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None
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Sample Rejection:
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Patient on heparin or collection in a heparin containing tube; specimens greater than 24 hours old or received frozen; clotted specimens; insufficient volume; mislabeled or unlabeled specimens
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Interpretive
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Reference Range:
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0 Bethesda Units/mL (Beth U/mL)
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Critical Values:
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N/A
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Limitations:
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Recent Factor 8 infusion may invalidate results.
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Methodology:
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Measurement of residual factor 8 on mixtures of patient plasma mixed with Other Factor 8 concentrate and incubated for 2 hours at 37ºC.
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References:
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Fairview University Laboratory Web Page June 2011
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Updates:
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6/2/2004: Draw volume changed from three 5 mL tubes to three 3 mL tubes.
5/24/2010: Tubing of patient specimens is no longer prohibited.
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