Photo-optical clot determination with Factor XII deficient substrate.
Detection of specific coagulation factor XII deficiency
50-150% of normal activity.
- Factor XII Assay
- Factor XII:C Assay
- Factor 12 Activity
- Factor 12 Assay
Collect specimen in a blue top (citrate 3.2%) tube. Mix by inversion. Specimen should arrive at lab within 3 hours of collection; transport at room temperature. Alternatively, centrifuge, aliquot plasma into a plastic vial, and freeze the specimen within 4 hours of collection. Transport frozen specimen on dry ice. Collection of the blood through lines that have been previously flushed with heparin should be avoided. If the blood must be drawn through a VAD (vascular access device), the line should be flushed with 5 mL of saline and the first 5 mL of blood or six dead space volumes of the VAD discarded.
Deficiencies have no hemorrhagic consequence. Factor XII may be increased in patients with pre-eclampsia and decreased in patients with liver disease, renal disease, and Rocky Mountain spotted fever. Congenital Factor XII deficiency has been associated with an increased incidence of venous thrombosis.