Assay is included in the Von Willebrand Panel.

1 Day

Batched once per day. Must be in Core Lab by 7:00 AM. Call 503-494-7383 if STAT.

3.2% sodium citrate tubes are acceptable when they are filed to the line on the manufacturers label. Tubes must be full (see comments below). For referral testing, submit 2 x 1.0 mL frozen platelet poor citrated plasma.

Sodium citrate specimens must be processed and frozen within 2 hours of specimen collection.

OHSU clinics must cab specimen to the Core Lab, Hatfield Research Center (HRC), Room 9D05 if processing is delayed or not possible on site. A phone call is helpful to alert the lab at 503-494-5764.

Detailed instructions are under the Hemostasis & Thrombosis section (Opens in a new window).

Add blood to the 1.3 mL mark of Pediatric BLUE top tube, 3.2% sodium citrate. For pediatric patients requiring multiple coagulation tests, please call 503-494-7383 regarding draw volumes.

Reference Range: 50% to 150%

Draw volume is critical due to the liquid anticoagulant. Allow tubes to fill by vacuum.

• Tubes with rubber stopper: fill to line on label.
• Tubes with plastic (Hemogard) cap: the fill level is above the top of the label.
• Syringe: do not remove the vacutainer stopper. Insert the needle through the stopper and allow the tube to fill by vacuum. Do not overfill the vacutainer.
• Pediatric tubes have no vacuum. Remove the cap and add blood to the 1.3 mL mark. Do not overfill.

Avoid warfarin (Coumadin) therapy for 2 weeks and heparin therapy for 2 days prior to the test.

Use: detect coagulant factor VIII deficiency. Factor VIII deficiency (Hemophilia A) is the most common of the hereditary bleeding disorders. Deficiences of factor VIII are inherited as sex-linked recessive disorders. Factor VIII is a molecular complex consisting of VIII:C, which corrects the abnormal clotting time, and VIII:R the "related protein" (the von Willebrand protein) which corrects the defect in von Willebrand disease. VIII:C portion of the complex is a glycoprotein with molecular weight of about 285,000. There are both VIII:C deficient patients (CRM-type also named hemophilia A-, the common form) and VIII:C nonfunctional molecular variant patients (CRM+ type also named hemophilia A+).

Female patients with VWD on oral contraceptives or who are pregnant may have normal F. VIII values. F. VIII is also an acute-phase reactant and is elevated with stress or exercise.

F8A
Factor 8
Factor VIII
FVIIIA