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Lab Dept:
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Coagulation
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Test Name:
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FACTOR VIII (FAIRVIEW UNIVERSITY)
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General Information
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Lab Order Codes:
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F8U
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Synonyms:
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AHF; AHG; Antihemophiliac Factor; FVIII; VIII:C; Hemophilia A; Factor VIII Assay
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CPT Codes:
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85240 – Clotting; factor VIII (AHG), one stage
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Test Includes:
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Factor VIII activity reported as a %.
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Logistics
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Test Indications:
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Useful for the detection of a single congenital homozygous or heterozygous factor deficiency for Hemophilia A or von Willebrand’s disease or an acquired deficiency due to liver disease or DIC.
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Lab Testing Section:
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Sendouts - Coagulation
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Referred to:
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Fairview University Medical Center (Test# F8)
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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 hours if received on Monday – Friday: 0700-1730 or Saturday: 1000-1300. 1 day if received outside of these regular working hours. Stats are done within 1 hour of receipt in the laboratory.
For urgent testing after hours, contact Children’s laboratory and they will call Fairview’s tech on call.
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Special Instructions:
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Patient should not be receiving heparin. If so, this should be noted on the request form. Heparin therapy can affect certain coagulation factors or assays, preclude their performance, or cause spurious results.
Indicate when specimen is drawn from a line or a heparin lock. Deliver immediately to the laboratory.
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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
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Processed Volume:
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Specimen will be processed by 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.
Patients with Hematocrit levels of >55% must have a special tube made to adjust for the hematocrit, contact laboratory for special tube.
Fill tube completely. Mix thoroughly by gentle inversion.
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Special Processing:
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Lab Staff: Do Not centrifuge. Send to reference lab in original Vacutainer®. Must arrive in reference lab within 24 hours of collection.
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Patient Preparation:
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If the patient has a coagulation abnormality, apply direct pressure to the puncture site for 10 minutes; apply pressure bandage. Instruct the patient to leave the bandage on for 12 hours.
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Sample Rejection:
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Improper tube; clotted samples; underfilled tubes; overfilled tubes, mislabeled or unlabeled specimens
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Interpretive
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Reference Range:
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Age:
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Range (%):
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<1 day:
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61 – 194%
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1 – 4 days:
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61 – 139%
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5 – 29 days:
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55 – 121%
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30 – 89 days:
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58 – 124%
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90 – 179 days:
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56 – 102%
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180 – 364 days:
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55 – 91%
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≥1 year:
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60 - 140%
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Critical Values:
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N/A
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Limitations:
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Increased in patients who are pregnant or are taking oral contraceptives
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Methodology:
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APTT clotting time correction of factor 8 deficient plasma. Patient dilutions are compared to a known set of standard dilutions and a percentage is determined.
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References:
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Fairview University Web Page June 2011
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Harmening DH (1997) Clinical Hematology and Fundamentals of Hemostasis
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Updates:
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5/27/2004: Reference ranges changed from 70-130% to 60-140%. Draw volume reduced from 4.5 mL in a 5 mL tube to 2.7 mL in a 3 mL tube.
10/7/2005: Reference ranges added for 0-5 days, previously only listed for greater than or equal to 1 year.
5/25/2010: Tubing patient specimens is no longer prohibited.
6/15/2011: Reference range update.
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