• Evaluation of an elevated aPTT
• Measurement of high molecular weight kininogen concentration

 Lt blue Sodium citrate (NaCit) - 2.7mL x 2

• Do not draw from an arm with a heparin lock or heparinized catheter.
• Blood should be collected in a blue top tube containing 3.2% buffered sodium citrate. 
• Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.
• Immediately following collection, mix sample thoroughly by gently inverting 8 - 10, times to prevent clotting
• A discard tube is not required prior to collection of coagulation samples except when using a winged blood collection device (i.e. "butterfly"), in which case a discard tube should be used.
• When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes.
• Any tube containing an alternate anticoagulant should be collected after the blue top tube.
• Serum gel tubes with clot initiators should also be collected after the citrate tubes.

1. Spin 
2. Transfer the plasma into a Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp), labelled as Na cit plasma
3. Freeze immediately 

Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp)

Clot-based

65 - 135%