Protein S, Free Antigen with Reflex to Protein S, Total Antigen
Ordering Recommendation
Use to detect and subtype protein S deficiency. Do not order if individual has been on warfarin therapy in the previous 2-4 weeks.
Submit With Order
Microlatex Particle-Mediated Immunoassay
1-4 days
New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Lt. blue (sodium citrate). Refer to Specimen Handling at for hemostasis/thrombosis specimen handling guidelines.  
Specimen Preparation
Transfer 2 mL platelet-poor plasma to an ARUP Standard Transport Tube. (Min: 1 mL)  
Storage/Transport Temperature
CRITICAL FROZEN. Separate specimens must be submitted when multiple tests are ordered.  
Unacceptable Conditions
Serum. Non-frozen or hemolyzed specimens.  
Ambient: 4 hours; Refrigerated: Unacceptable; Frozen at -20°C: 3 months, at -70°C: 6 months  
Reference Interval
1-89 days: 15-55%
90-179 days: 35-92%
180-364 days: 45-115%
1-5 years: 62-120%
6-9 years: 62-130%
10-17 years: 60-140%
18 years and older Male: 74-147%
18 years and older Female: 55-123%
Interpretive Data
Patients on warfarin may have decreased free protein S values. Patients should be off warfarin therapy for two weeks for accurate measurement of free protein S levels. Decreased levels of free protein S are also associated with DIC, liver disease, pregnancy, and inflammatory syndromes.
If low Protein S Free Antigen is detected, then Protein S, Total Antigen, will be added. Additional charges apply.
CPT Code(s)
85306; if reflexed, add: 85305
Component Test Code*Component Chart Name
0098894Protein S Ag Free
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Cross References
  • Protein S Profile
  • Protein S, Free and Total Antigen