Ordering Recommendation

Recommended test to detect protein C deficiency. Do not order if individual has been on warfarin in the previous 2-4 weeks.

New York DOH Approval Status

This test is New York state approved.

Specimen Required

Patient Preparation

Lt. blue (sodium citrate). Refer to Specimen Handling at aruplab.com for hemostasis/thrombosis specimen handling guidelines.

Specimen Preparation

Transfer 1.5 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.

Unacceptable Conditions

Serum. EDTA plasma, clotted or hemolyzed specimens.


Ambient: 4 hours; Refrigerated: Unacceptable; Frozen at -20°C: 3 months, at -70°C: 6 months


Electromagnetic Mechanical Clot Detection




1-2 days

Reference Interval

Effective November 17, 2014

Age Reference Interval
1-4 days 17-53%
5-29 days 20-64%
30-89 days 21-65%
90-179 days 28-80%
180-364 days 37-81%
1-6 years 40-92%
7-9 years 70-142%
10-11 years 68-143%
12-13 years 66-162%
14-15 years 69-170%
16-17 years 70-171%
18 years and older 83-168%

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.

Compliance Category



Hotline History


CPT Codes



Component Test Code* Component Chart Name LOINC
0030113 Protein C Functional 27819-2
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


  • Functional Protein C
  • Protein C Activity
  • Protein C, Functional, Plasma
Protein C, Functional