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Test Code Pr C Act Protein C Activity

Useful For

Protein C is present in the plasma as a pro-enzyme. Its transformation into an active enzyme requires the presence of thrombin, calcium and phospholipids.
This thrombin-dependent activation of Protein C is potentiated by an endothelial
factor, thrombomodulin. In the activated state, Protein C regulates the coagulation process by neutralizing the procoagulant activities of the factors Va
and VIIIa in the presence of cofactor Protein S. This limits thrombus extension and acts as a major regulator of the coagulation process Protein C belongs to the
Vitamin K-dependent proteins. It is synthesized in the liver. Production of a functional Protein C molecule depends on the carboxylation of the glutamic
residues of a precursor molecule by a hepatic carboxylase. The cofactor of the
hepatic carboxylase is Vitamin K. In case of a Vitamin K deficiency, this carboxylation is reduced, and the inactive precursor appears in circulation.

Patient Preparation

No special patient preparation required

Special Collection Instructions

Properly filled 9:1 ratio (blood to anticoagulant); 3.2% NaCitrate tube

Collection Method

Venous Draw; properly filled 9:1 ratio (blood to anticoagulant)

Minimum Volume

0.5 ml of plasma from a properly filled 1.8 mL or 2.7 mL NaCitrate (light blue) tube

Container

Light Blue Sodium Citrate
 

Preferred Specimen

2.7mL Lt. Blue (3.2% NaCitrate)

Acceptable Specimens

1.8 mL Lt. Blue (3.2% NaCitrate) tube

Reference or Target Ranges

70 - 140%

Reportable Units

% (percentage)

Critical Value

Not defined for this assay

Reasons for Rejection

Hemolysis Threshold N/A
Icterus Threshold N/A
Lipemia Threshold N/A
Interfering Subtances/Other Short draws, over draws, clotted, improperly labeled, hemolyzed, lipemic or icteric samples, samples > 4 hours from collection

Specimen Stability

Ambient Plasma – 4 hours
Refrigerated (4°C to 8°C) N/A
Frozen(-70°C to -20°C) 2 weeks@ -20°C; 1 year @ -70°C

Performance Information

Days and Time Performed Batched weekly Monday-Friday
Expected Turn Around Time Batched Monday – Friday
Stat Availability No
Performing Bench Coagulation
Methodology/Method Description Werfen ACL TOPS - Chromogenic Assay

Additional Information/Important Notes

After being spun down, separated plasma must be transported to University Hospital Laboratory frozen on dry ice.

CPT Codes

85303

Special Handling

Centrifugation: 5 minutes at 5000 rpm. Plasma must be centrifuged twice
(double spun) to remove platelets. (<10,000 mm3)