5932 Protein C Antigen

Components
NAME METHOD REFERENCE RANGE UNITS
Protein C Antigen EIA  65 - 140  % 


Specimen Requirements
TYPE VOLUME TEMPERATURE INSTRUCTIONS
PRIMARY
1 Plasma Citrated 1 (0.5) mL   Frozen - 14 Day(s) See COLLECTION INSTRUCTIONS for platelet-poor plasma. 


Clinical utility
Congenital Protein C deficiency is characterized by recurrent venous thrombosis and thromboembolism beginning in adolescence. Type I is characterized by reduction in both antigenic and functional levels, whereas in Type II functional levels are decreased much more than antigenic levels.


Collection Instruction
Instructions for platelet-poor plasma:
1. Draw a plain red top tube to remove tissue fluid contamination.
Discard this tube.
2. Draw blood into a buffered citrate collection tube (light blue
top) filled to proper level. Do not overfill.
3. The blood-to-anticoagulant ratio should be 9:1; inadequate
filling of the collection device will decrease this ratio and
may lead to inaccurate results.
4. Adjust the final citrate concentration in the blood of
patients who have hematocrit values above 0.55 (55%). For
hematocrits below 20%, there is no current data to
support a recommendation for adjusting the citrate concentration.
5. The needle gauge could be between 19-22. For pediatric
patients a 21-23 gauge needle may be used.
6. Invert gently 6 times to mix. Process immediately.
7. Centrifuge for 15 min at 2500 x g.
8. Remove plasma using a plastic pipette to transfer into a
new tube.
9. Repeat centrifugation at 2500 x g for 15 minutes to assure
complete platelet removal.
10. Dispense the plasma into 2 or more plastic tubes using a
plastic transfer pipette. Label tubes appropriately.
11. Freeze immediately at -70 C.
12. Specimen must remain frozen at all times. Ship to Specialty
within 24 hours on dry ice.
13. Specimen should not be submitted if:
* it is hemolyzed
* microclots are present
* the tube is less than 90% filled
* a specimen with hematocrit >55% is collected without anticoagulant
adjustment.


Reported: Same day

CPT Code: 85302

Notes: Heparin concentrations of greater than or equal to 1 IU/mL can lead to higher values of Protein C activity. Protein C is a vitamin K dependant factor. Patients on coumadin will have lower levels of Protein C. Falsely low Protein C activities may be obtained in patients undergoing treatment with aprotinin.