Hemostasis Reference Laboratory

Factor VII Activity

• Transaction Code: 3210-12
• CPT Code (Suggested): 85230

A one-stage extrinsic system clotting assay is used to measure circulating factor VII level. Clotting times of dilutions of patient plasma are compared to dilutions of a plasma pool from normal donors, when added to deficient plasma. Levels are reduced by hereditary or acquired factor VII deficiency, vitamin K deficiency, liver disease, warfarin therapy, or disseminated intravascular coagulation (DIC). A common polymorphism can account for mildly reduced levels when heterozygous; homozygotes average 30-40% with normal hemostasis. In epidemiologic studies, low - normal factor VII levels are correlated with reduced risk of coronary artery thrombosis but this is of little predictive value for individual patients.

• Sample Required: 0.5 ml frozen plasma x4 or (2) 3.2% sodium citrated tubes, 5 ml each.
• See Sample Requirements when ordered with other tests.
• Normal Range: 60-137% effective 11/1/11
• Analytic Time: Performed weekly, available STAT