ARUP's Laboratory Test Directory

Protein C, Functional with Reflex to Protein C, Total Antigen : 0030041

Mnemonic: PROT CF R

Ordering Recommendation: Acceptable test to detect and subtype protein C deficiency. Do not order if individual has been on warfarin therapy in the previous 2-4 weeks.
Methodology: Clotting/Enzyme-Linked Immunosorbent Assay
Performed: Sun-Sat
Reported: 1-5 days
Specimen Required: Collect: Lt. blue (sodium citrate). Refer to Specimen Handling at aruplab.com for hemostasis/thrombosis specimen handling guidelines.

Specimen Preparation: Transfer 2 mL platelet-poor plasma to an ARUP Standard Transport Tube. (Min: 1 mL)

Storage/Transport Temperature: CRITICAL FROZEN. Separate specimens must be submitted when multiple tests are ordered.

Remarks:

Unacceptable Conditions: Serum. Non-frozen or hemolyzed specimens. Anticoagulants other than citrate.

Stability (collection to initiation of testing): Ambient: 4 hours; Refrigerated: Unacceptable; Frozen at -20°C: 3 months, at -70°C: 6 months
Reference Interval:
By report
Interpretive Data: Patients on warfarin may have decreased protein C values. Patients should be off warfarin therapy for two weeks for accurate measurement of protein C levels. Artificially increased functional protein C values may be due to heparin therapy or the presence of direct thrombin inhibitors or factor Xa inhibitors.
Note: If Protein C functional is decreased, then Protein C, Total Antigen, will be added. Additional charges apply.
CPT Code(s): 85303; if reflexed, add 85302
Cross References: Protein C Profile (Protein C, Functional with Reflex to Protein C, Total Antigen)