Introduction: Factor Deficiencies
A deficiency in one or more coagulation factor will also cause abnormalities in hemostasis. The image to the right depicts the coagulation cascade. Notice how one factor acts upon another to eventually form a stabilized fibrin clot, the end product of the coagulation cascade. Having an abnormally low level, or a complete lack, of a coagulation factor can cause the extrinsic, intrinsic, or common pathways to malfunction, resulting in dangerous hemorrhagic issues including spontaneous bleeding.
Two of the most common factor deficiencies are factor VIII (hemophilia A) and factor IX (hemophilia B). Hemophilia A comes in two forms: congenital (inherited) or acquired. Congenital hemophilia A represents the condition where an individual is born defecient (to various degrees) of factor VIII. Acquired hemophilia A is a condition in which an individual spontaneously produced an autoantibody to factor VIII, leaving the body unable to use the factor VIII that may be present. Hemophilia B is an inherited condition where the individual has a mutation of the factor IX gene and is unable to produce adequate levels of this coagulation factor.
In some cases, patients have multiple factor deficiencies that are secondary to a primary condition such as vitamin K deficiency, disseminated intravascular coagulation (DIC), and liver disease. With vitamin K deficiency, the liver is unable to produce the coagulation factors that are vitamin K-dependent. During liver disease, the liver may be unable to produce coagulation factors effectively. In DIC, the clotting processes are in overdrive and will consume the coagulation factors that are being produced, leading to low levels of circulating coagulation factors.