5938 Protein S Evaluation

Protein S Activity CLOT DET  65 - 140  % 
Protein S Antigen Total LIA  70 - 140  % 

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

Clinical utility
Hereditary protein S deficiency is associated with recurrent venous thromboembolic disease often presenting in adolescents or young adults. Protein S levels are low in pregnancy and coumadin therapy. Acquired Protein S deficiency is documented in DIC, Type I and II diabetes mellitus, pregnancy, oral contraceptive use, nephrotic syndrome, liver disease, and essential thrombocythemia. Three types of congenital protein S deficiency have been identified: Type I with reduced total and free protein S antigen, Type II with reduced activity but normal free and total antigen, and Type III with reduced activity of protein S and reduced free protein S, but normal total protein S antigen.

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. Stable for 1 month at -20 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

Reported: Same day

CPT Code: 85305, 85306

Notes: Rheumatoid factor (RF) as well as lipemia may interfere with test results. High levels of heparin, fibrinogen, Factor VIII activity, as well as Lupus Anticoagulants (LA) may yield falsely low protein S results.