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Aug 1, 2016

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UWHC,UWMF,

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

Protein S Ag, Free

Protein S Ag, Free (HCPSFREE) Coagulation Lab Test

Name: Protein S Ag, Free

Test Name: Protein S Ag, Free

Health Link Test Code: HCPSFREE

LIS Test Code: PSFREE

CPT Code(s): 85306

Methodology: Immunoturbidimetry

Days Performed: Mon-Fri, dayshift - day varies.

In-Lab Turnaround Time: 1 - 2 weeks.

Stat In-Lab Turnaround Time: Not available stat.

Patient Preparation:

Patient must be off warfarin therapy for at least one week or on a stable dose of warfarin for at least one week.

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.

 

Indicate if patient is receiving anticoagulant (warfarin/ Heparin/Vitamin K antagonist), direct thrombin inhibitor or fibrinolytic agent therapy.

Collection Volume: Full 3.5 mL tube

Pediatric Collection Volume: Pediatric tube filled to fill mark

Stability Ambient:

4 hours on a spun tube

Stability Refridgerated:

Not acceptable

Stability Frozen:

2 weeks at -20°C; 6 months at -70°C

Sample Analyzed: Plasma

Testing Volume: 1 mL

Pediatric Testing Volume: 0.3 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.

Outreach Specimen Processing:

Centrifuge specimen to yield platelet poor plasma (platelet count should be 10 K/µL or less). Separate plasma and transfer to labeled plastic tube and spin again. Transfer plasma from second spin to clean plastic labeled tube or vial. Indicate on tube "spun twice". 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. Specimens from patients who have not been off warfarin therapy for at least one week or on a stable dose of warfarin for at least one week are not acceptable.

Interpretation:

 MALES  
 6 months and up 74-146 %NPP
   
 FEMALES  
6 months and up  55-124 %NPP

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

Interpretation Type: Reference Interval

Test Limitations:

The presence of rheumatoid factor, anti-bovine albumin and/or anti-mouse antibodies in certain subjects may have a falsely elevated level of Free Protein S.

Additional Information:

A clotting test for Protein S (functional portion) is also available (see Protein S Activity).

Free Protein S is not affected by Factor V Leiden mutation.