Accurate filling of specimen tube essential.
Specimens must be transported at room temperature to the Laboratory in a red specimen bag ASAP. (Maximum delay to testing laboratory must not exceed 2hrs)

* If several factor assays are requested, e.g. VIII, IX, XI, and XII, 3 x sodium citrate tubes are required for an adult and 2 tubes for a child.

Factor VIII has a circulating half-life of 8-12 hours. Congenital deficiency is seen in Haemohilia A and von Willebrand's disease (type 3 von Willebrand's disease may have F VIII levels similar to those that are found in severe Haemophilia A). A female patient with F VIII deficiency is more likely to have von Willebrand's disease (especially von Willebrand type 2N), although female carriers of the Haemophilia A gene may develop a bleeding tendency due to low F VIII levels - family history is important. NOTE: In von Willebrand's disease, Factor VIII levels may not be sufficiently decreased to cause a prolonged aPTT!
Factor VIII is not produced in the liver (unlike the other coagulation factors) and levels are normal or increased with liver disease (the protein is an acute phase protein). This information may be of value when one has to distinguish between consumption coagulopathy (DIC) and liver disease.