Veripath Test Directory

Synonyms Factor VIII Assay, Antihemophilic Factor VIII
Description Factor VIII is a plasma glycoprotein, synthesized by the specialized endothelium of liver sinusoids Factor VIII circulates in plasma in a noncovalent complex with von Willebrand Factor. Congenlial deficiency of FVIII leads to Hemophilia A, an inherited sex-linked recessive disorder that causes bleeding diathesis. Factor VIII activity in patient's plasma is determined by performing a modified activated partial thromplaslin time test (aPTT).
Specimen Requirements 
Container Light blue (3.2% sodium citrate) collection tube
Specimen Type Blood
Preferred Collection Volume 3 mL
Minimum Collection Volume Adult: 2 mL, Neonates : 2 mL
Collection Instructions 1. When drawing specimens for coagulation testing, always draw a "pilot" tube (7-10mL plain red top tube), completely filled. This removes tissue fluid contamination. Discard pilot tube.
2. Draw blood in a light blue top tube (3.2% sodium citrate). Fill tubes as far as vacuum will fill and mix gently. Do not shake tube. Ratio of anticoagulant and blood must be maintained. Avoid slow flowing draws and traumatic venipunctures.
Specimen Handling In-house patients, transport at room temperature.
Outside clients, follow collection instructions and the steps below:
1. Spin light blue top tube. Remove plasma avoiding platelet/buffy layer. Spin plasma again to remove top portion of plasma and place 1 mL of PLATELET-POOR PLASMA in plastic tube. (Glass tube unacceptable).
2. Double-centrifugation is critical for accurate results as platelet contamination may cause erroneous results.
3. Plasma must be frozen within 4 hours of collection.
4. CRITICAL WARNING: Specimen must remain frozen until ready to be tested. Submit separate aliquots when multiple tests are ordered on same patient specimen.
Rejection Criteria Hemolysis, contamination with heparin, clotted, short sample, >4 hrs old
Methodology Clotting based assay
Reference Range 50-150%
CPT Code(s) 85240
Department Hemostasis/Coagulation
Contact Information Special Coagulation Lab: 214-645-5346; Customer Service: 214-645-7057, Toll Free 877-887-8136
Turn Around Time1 day
Performed Sunday - Saturday
Performed by Special Coagulation
Updated/Reviewed 07/25/2016