Clinics and Departments

Laboratory Services

Lab Dept:

Coagulation

Test Name:

PROTEIN C CHROMOGENIC (FAIRVIEW UNIVERSITY)

General Information

Lab Order Codes:

PTC

Synonyms:

Protein C Activity Assay; Protein C Immunologic Assay

CPT Codes:

85303 – Clotting inhibitors or anticoagulants; Protein C activity

Test Includes:

Protein C activity

Logistics

Test Indications:

Protein C, along with its cofactor Protein S, acts as a potent anticoagulant by destroying activated Factors 5 and 8. It is Vitamin K dependent, therefore it is decreased in coumadin therapy or Vitamin K deficiency. Protein C deficiency is a risk factor for thromboembolism. Severe deficiency may cause purpura fulminans in neonates. It is best not to test for Protein C deficiency during an acute thrombotic event. The Protein C Chromogenic (activity) assay determines amount of functional Protein C.

Lab Testing Section:

Coagulation - Sendouts

Referred to:

Fairview University Medical Center (Test# PCCH)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

Within 2 days; test set up one to two times per week, Monday - Friday

Special Instructions:

INR is needed for interpretation (Protein C is decreased in Coumadin therapy/Vitamin K deficiency).

Specimen

Specimen Type:

Whole blood

Container:

Light Blue top tube (Buffered Na Citrate 3.2%)

Draw Volume:

2.7 mL (Minimum: 1.8 mL) blood

Processed Volume:

Specimens will be processed at reference lab facility if received within 4 hours of collection. Otherwise, specimens need to be processed at referring facility and provide minimum of two 0.5 mL specimens frozen at -70. Follow directions below under Special Processing.

Collection:

Do Not use the first 2 mL of blood collected.

If the patient’s hematocrit is >55%, contact laboratory to obtain a special tube.

Fill tube completely. Mix thoroughly by gentle inversion.

Special Processing:

Lab Staff: Do Not centrifuge. Do Not freeze. Send to reference lab in original Vacutainer® at room temperature if within 4 hours of collection. Forward promptly.

If specimen is >4 hours old prior to shipment, process specimen as follows:
Spin sample collected in blue top tube(s) for 5 minutes on the Stat Spin centrifuge, remove plasma and transfer to a 4 mL BCS sample cup(s), spin remaining plasma again for 5 minutes in the Stat Spin Centrifuge. Transfer plasma into two labeled 10x75 mL plastic tubes with a minimum of 0.5 mL in each. Freeze at -70 and send specimens on dry ice to Fairview University.

Patient Preparation:

If the patient is being treated with Coumadin®, this should be noted. Coumadin® will lower Protein C.

Sample Rejection:

Improper tube; clotted sample; overfilled tube; underfilled tube; lipemic sample; mislabeled or unlabeled specimens

Interpretive

Reference Range:

Age

Range (%)

0 days

14 – 42%

1 day

26 – 44 %

5 days

31 – 53%

30 days

32 – 54%

90 days

41 – 67%

180 days

48 – 70%

1 years

40 – 92%

6 years

45 – 93%

11 years

55 –111%

17 years and older

70 – 170%

Critical Values:

Less than 20% (for 5 days and older)

Limitations:

This assay cannot be performed if the patient is receiving heparin. Heparin interferes with amyloidosis of the substrate. Lipemic samples are not acceptable. Coumadin® will lower Protein C.

Methodology:

Chromogenic (synthetic substrate) activity assay

Contraindications:

Patient cannot be receiving lipids or heparin.

References:

Fairview University Medical Center Web Page http://labguide.fairview.org/diagnostic.asp February 2014

Harmening DH (1997) Clinical Hematology and Fundamentals of Hemostasis

Update

2/25/2014: Fairview specimen processing update.
3/24/2014: Fairview reference range update.



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