Aug 1, 2016




Clinical Hub,Tools & Resources,UWHC Lab Test Directory,Coagulation

Protein S Activity

Protein S Activity (XPSF) Coagulation Lab Test

Name: Protein S Activity

Test Name: Protein S Activity

Health Link Test Code: XPSF

LIS Test Code: PS-ACT

CPT Code(s): 85306

Methodology: Photo-Optical Clot Detection

Clinical Information:

Test is used for the qualitative determination of plasma Protein S activity by clotting method.

Days Performed: Mon-Fri, dayshift - day varies. Specimens are accepted at any time. Testing required during off hours must be approved by a Coagulation physician. Call 263-5005 before collection.

In-Lab Turnaround Time: 1 - 2 weeks.

Stat In-Lab Turnaround Time: 1 day.

Patient Preparation:

Patient must be off warfarin therapy for at least one week. See additional information below.

Specimen: Blood

Collection Container: Light blue top (3.2% NaCitrate)

Collection Instructions:

Do NOT draw through a line containing heparin. The venipuncture MUST be atraumatic to avoid hemolysis and contamination with tissue factors and platelets. Tube must be allowed to fill completely.


Please indicate patient history and if patient is receiving anticoagulant (warfarin/ Heparin/Vitamin K antagonist), direct thrombin inhibitor or fibrinolytic agent therapy and duration.

Collection Volume: Full 3.5 mL tube

Pediatric Collection Volume: Pediatric tube filled to fill mark

Stability Ambient:

4 hours on spun tube

Stability Refridgerated:

Not acceptable

Stability Frozen:

2 weeks at -20°C; 6 months at -70°C

Sample Analyzed: Plasma

Testing Volume: 1.5 mL

Pediatric Testing Volume: 0.5 mL

Specimen Processing:

Centrifuge specimen to yield platelet poor plasma (platelet count should be less than 10 K/uL). Separate plasma and transfer to plastic tube or vial. Freeze plasma within 4 hours of collection at -20°C or below.

Specimen Transport:

Transport whole blood specimen at room temperature to UWHC Hospital Laboratory within 4 hours of collection. See Specimen Processing for instructions if transport criteria are not met. Transport frozen plasma aliquot on dry ice to UWHC Hospital Laboratory.

Unacceptable Criteria:

Hemolyzed specimens, clotted specimens, partially filled tubes and whole blood specimens greater than 4 hours old when received by the laboratory are not acceptable. Test cannot be done if patient is receiving coumadin.



6 months and up:  63.0-150.0 %NPP

Age and hormonal states my affect the normal range for females.

Normal, full-term newborn infants or healthy premature infants may have decreased levels of total Protein S (15-50%); but because of the the low levels of C4bBP, free Protein S may be normal or near the normal adult level (>or=50%). Total Protein S reaches adult levels by 90-180 days postnatal.




Interpretation Type: Reference Interval

Test Limitations:

Patients on oral anticoagulants will have deceased functional protein S values. Patients should be off of oral anticoagulant therapy for one week for accurate functional protein S levels.

Artifactually elevated levels of functional Protein S may be seen in samples with very high heparin levels or the presence of thrombin inhibitors.