Measurement of prekallikrein factor concentration
Do not draw from an arm with a heparin lock or heparinized catheter.
Spin, separate, and freeze
Ambient - 4 hours
Factor prekallikrein activity is determined utilizing an aPTT-based one-stage clotting time assay. Factor prekallikrein-depleted plasma is used as the substrate, and the clotting time with the patient plasma is compared to the clotting time of normal pooled plasma.
Normal: ≥ 50 %