Protein C Activity (CAC)
Department: Coagulation
Test Synonym(s): LAB489, CAC, PC Act
CPT Codes: 85303
Methodology: Chromogenic
Reference Range: 50 - 120%
Tube Type: Light blue top (Sodium Citrate)
Specimen: Citrated platelet poor plasma - Requires double centrifugation if sending a plasma aliquot. Aliquot(s) must be frozen if not received by lab within 4 hours of collection.
Alternate Specimen: None
Pediatric Requirements: Pediatric: One 2.7mL Light blue top - 3.2% Sodium Citrate. Neonatal: One 1.8mL Light blue top - 3.2% Sodium Citrate.
Volume: 1.0 mL plasma
Minimum Volume: 1.0 mL plasma
Temperature: Room Temperature for Light blue top tube, must be received within 4 hours of draw. Plasma aliquot(s) must be frozen if not received by lab within 4 hours of collection.
Stability: Room temperature: 4 hours, Frozen: -70 C for one month
Reasons for Rejection: Clotted sample, incorrectly filled tubes, incorrect tube type, grossly hemolyzed sample, grossly lipemic sample, grossly icteric sample, whole blood >4.0 hours old
Days Performed: Monday - Friday
Times Performed: 8:00 a.m. - 3:00 p.m.
TAT: 1 day
Significance: Therapeutic warfarin results in a decreased level of Protein C. Presence of Aprotinin in the sample will result in an under estimation of the Protein C level.
Special Instructions: Indwelling line should be flushed with saline and 5.0 mL of blood discarded before collecting samples for coagulation assays.Tube must be full and not clotted. Deliver to lab immediately. Samples received from an outside lab must be aliqouted and frozen. Samples aliquoted for shipping must be double centrifuged prior to freezing. Grossly hemolyzed, icteric or lipemic samples may be rejected. Levels of functional protein C will be decreased in patients taking Warfarin drugs. Patients should be off anticoagulant therapy prior to measuring protein C levels.
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