Geisinger Medical Laboratories/Geisinger Proven Diagnostics Test Catalog

Order Display Name: Geisinger Epic Procedure Code Or ID CPT Code:  

PROTEIN C ACTIVITY

ORDERING INFORMATION:
Geisinger Epic Procedure Code: LAB2932         Geisinger Epic ID: 17588

SPECIMEN COLLECTION
Specimen type:
 Platelet-free plasma
Preferred collection container:
Alternate Collection Container:
Other size blue-top (3.2% sodium citrate) tubes (e.g., 1.8 mL, 4.5 mL)
Specimen required:
1 mL aliquot plasma
Special notes:
  • Ideally the patient should not be receiving anticoagulant medication as it may interfere with testing and cause erroneous results. See Anticoagulation Impact on Coagulation Tests.
  • If the patient’s hematocrit (HCT) is >55%, the volume of anticoagulant in the tube should be adjusted. Contact a performing location for special tube preparation to reduce the citrate in the collection tube. For those patients with HCT >70.0% see LAB3632 Stago Sodium Citrate Adjustment Chart for formula to determine amount of citrate removal required.
  • When possible, use fresh venipuncture to collect blood to avoid activation of coagulation by tissue thromboplastin. Blood may be drawn from an indwelling catheter or vascular access device. Draw sample from a lumen that has not been heparinized or flush the line with 5 mL of saline, and discard or use for other purposes the first 5-10 mL of blood.
  • Butterfly device collections, draw a discard tube first to remove air from collection tubing.
  • Tubes should be >90% filled.
  • Immediately mix gently after collection by inverting the tube end over end 5 to 6 times. Avoid vigorous mixing or additional inversion. Observe for the presence of clots. Recollect if fibrin clots observed.
  • Transport at ambient temperature to processing location and processing should be completed within 8 hours.
  • If plasma is icteric, lipemic or hemolyzed, a lab comment should be generated to notify staff.
Patient preparation:
 Patient must be off Coumadin 2 weeks prior to testing.
SPECIMEN PROCESSING
Specimen processing instructions:
Centrifuge the citrated blue-top tubes immediately at designated time and speed to obtain platelet free plasma (<10,000/µL). Using a plastic pipette, carefully remove plasma from cells, avoiding platelet/buffy layer by leaving a thin layer of plasma on top the cells. The centrifuged plasma should be aliquoted (1 mL per aliquot) into clearly labeled polypropylene tubes. The number of tests ordered will determine the aliquots needed. Check the residual specimen for clot and if present discard sample and redraw specimen. Freeze upright and transport on dry ice.. 
Transport temperature:
 Frozen.
Specimen stability:
 Room temperature: 8 hours. Frozen: -20°C for 30 days, -70°C for 6 months.
Rejection criteria:
 Clotted specimen. Stability exceeded. Overfilled or underfilled tubes. HCT > 55% and anticoagulant ratio not adjusted. Severely hemolyzed. Grossly icteric or lipemic can interfere with assay and may be rejected if interference is suspected.
Note: Specimen suspected of thawing in transport, indicated by slant in aliquot or specimen in lid of tube, will have testing performed, and the comment “interpret results with caution as thawing suspected” added to results.
TEST DETAILS
Reference interval:
 75-135
Additional information:
 Anticoagulation Impact on Coagulation Tests
CPT code(s):
 85303
Note: The billing party has sole responsibility for CPT coding.  Any questions regarding coding should be directed to the payer being billed.  The CPT codes provided by GML are based on AMA guidelines and are for informational purposes only.
Test includes:
 Protein C activity.
Methodology:
Chromogenic
Synonyms:
Functional Protein C, PROTC
Clinical significance:
Deficiency of protein C is a risk factor for venous thrombosis. Low levels may be acquired or congenital. Acquired levels are from recent Coumadin therapy within 10 days, vitamin K deficiency, liver dysfunction, DIC, recent thrombosis or recent surgery.
Doctoral Director(s:)
Michelle Grant DO    
Review Date: 01/12/2021

Performing Locations

Geisinger Medical Center

Performing laboratory: Coagulation
Technical Lead: Margaret Knowles-Tuchman
Frequency: Daily, first shift
Performed STAT? No
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