Factor VIII Activity Assay

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Primary Name	Factor VIII Assay
Synonym	Factor VIII functional assay
Synonym	Factor VIII activity assay
Contraction	FVIII
Contraction	FVIII:C
UAB Procedure Number	2500480
CPT Code	85240
Specimen	Collect one (1) blue-stopper tube (3.2% sodium citrate), filled to specified volume. Do not underfill or overfill.
Specimen Management	Note time of collection and time of last treatment if applicable. Centrifuge blue-stopper tube within one (1) hour of collection, separate plasma and test or quick-freeze at -70°C.
Specimen Accepted	Daily including weekends
Test Performed	Monday-Friday.
Available Stat?	Pathologist approval required.
Description	Congenital factor VIII deficiency, termed hemophilia A, is inherited as a sex-linked recessive and is seen in 1 in 5000 males. Factor VIII deficiency is also seen in some cases of von Willebrand disease. Rare inhibitors (autoantibodies) cause acquired factor VIII deficiency, usually in adults. Factor VIII deficiency is associated with mild to severe bleeding. Chronic elevated factor VIII confers a 2- to 3-fold risk of venous thrombosis. Because factor VIII is an acute phase reactant, a single elevated result may not alone indicate a risk of thrombosis.
Reference Interval	50-186%
Critical Value	None
Follow-up Test	If von Willebrand disease is suspected, the ristocetin cofactor (vWF activity) and von Willebrand factor antigen assays are recommended. If an anti-VIII inhibitor is suspected, an inhibitor titer (Bethesda titer) is recommended
Associated With	Bleeding disorders
Associated With	Venous thrombosis
Associated With	Von Willebrand disease