Protein S Antigen, Free
Label Mnemonic: PSAF
Epic code: LAB8982
Downtime form: Doctor/Provider Orders - Pathology Core and Specialty Care Nursery
Hematology
6240 RCP
356-3527
Specimen(s):
Plasma
Collection Medium:
Light Blue top tube 2.7 mL (Na Citrate)
Minimum:

Full draw, 2.7 mL light blue top tube

Rejection Criteria:

Short drawn tube, clot, traumatic tap (excessive hemolysis).

Testing Schedule:
0800-1630 Monday, Wednesday and Friday. If you need results STAT, call Hematology resident (0800-1630, M-F) at 356-8628. All other times page the Pathology resident on-call at 3404.
Turn Around Time:

1-3 days upon receipt in laboratory

Reference Range:

Females: 66-147%
Males: 73-139%

Interpretive Data:

Patients on warfarin may have decreased free protein S antigen concentrations. Warfarin therapy should be discontinued for at least two weeks prior to protein S testing. Decreased concentrations of free protein S antigen are also associated with liver disease, vitamin K deficiency, acute thrombosis, and DIC. Pregnancy, estrogen therapy, nephrotic syndrome, and inflammatory syndromes increase C4b binding protein concentrations, thus decreasing free protein S levels.

Methodology:

Immunoturbidimetric assay

CPT Code:
85306
 
See Additional Information:
Impact of Common Anticoagulants on Coagulation Tests