Hemostasis Reference Laboratory

Factor XI Activity

• Transaction Code: 3210-16
• CPT Code (Suggested): 85270

A one-stage intrinsic system clotting assay is used to measure circulating factor XI levels. 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 in hereditary factor XI deficiency (which is sometimes associated with a clinical bleeding tendency), or in the presence of a factor XI inhibitor, liver disease, or disseminated intravascular coagulation (DIC).

• 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: 77-136% effective 11/1/11
• Analytic Time: Performed weekly, available STAT