Factor 8 Activity


Abbrev Code:F8   
Order Code:LAB306Order Name:Factor 8 Assay
Synonyms:AHG (Antihemophilic Globulin); Anti-Hemophilic Factor; Factor VIII Activity
Methodology: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.
CPT Codes: 85240 x1, 85240 x1
Turnaround Time:Within 8 hours if received into the testing laboratory by 12 p.m. If ordered with von Willebrand Testing, results will be reported when the von Willebrand testing is complete. Testing performed 6 days per week. With pre-notification, STATs are done within 1 hour after receipt in the testing laboratory.
Special Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Associated Links:

Specimen Collection and Processing for Coagulation Specimens



Collection Instructions

Specimen:Blood
Optimal Volume:2.7 mL (in 3 mL tube) - filled to fill line on the tube.
Minimum\Peds Volume:2.7 mL (in 3 mL tube) - filled to fill line on the tube.
Container:Blue Na Citrate, 3.2% - fill to fill line on tube
Collection Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Causes for Rejection:Underfilled tubes, overfilled tubes, clotted specimens, not received or processed and frozen within 4 hours of collection or, specimen thawed during transit. Patients on Hemlibra® (emicizumab).


Processing and Shipping

Specimen Processing:
  • Process for Platelet Poor Plasma within 4 hours of collection.
  • Aliquot plasma, place clear tape around label, and freeze at -20C or on dry ice within 4 hours of collection.
  • If multiple tests are collected on 1 blue top, split each blue top into 2 aliquots. Minimum 0.5 mL per tube.
  • A maximum of 6 aliquots are needed per collection.
     
See link to Specimen Collection and Processing for Coagulation Specimens.
Shipping Instructions:
  • Ensure specimen is frozen before shipping.
  • Ship on dry ice, sample must remain frozen during shipping.
     
See link to Specimen Collection and Processing for Coagulation Specimens.
Test Performed at or Referral Lab UM Special Coag (K)  (UMMC East Bank)


Interpretive

Critical Range:Less than 10%
Reference Range:

Less than 1 d

61-194%

1-4 d

61-139%

5-29 d

55-121%

30-89 d

58-124%

90-179 d

56-102%

180-364 d

55-91%

1 y and older

55-200%

 

 

Use:

Factor 8 is an intrinsic coagulation pathway factor. Its congenital deficiency is commonly called Hemophilia A. The test is used to diagnosis Hemophilia A, von Willebrand’s Disease and acquired inhibitors to Factor 8. These conditions can lead to life-threatening bleeding. Also used to monitor various forms of Factor 8 concentrate infusion therapy.

 



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