Protein S, Functional
Label Mnemonic: PSFX
Epic Lab Code: LAB1135
Downtime Form: A-1a Miscellaneous Request
Hemostasis/Thrombosis
6240 RCP
356-3573
Specimen(s):
Collection Medium:
Light Blue top tube 2.7 mL (Na Citrate)
Minimum:
Full draw; 2.7 mL light blue top (mix well).
Rejection Criteria:
Short drawn tube, clot, traumatic tap (excessive hemolysis).
Delivery Instructions:
Deliver specimen to lab promptly. Usually performed every week.
Testing Schedule:
0800-1630 Monday through Friday. For additional services, contact Clinical Pathology Resident on-call at pager #3404.
Reference Range:
Males: 77-143%
Females: 55-123%
Comments:
Patient must be off anticoagulant medication (i.e. coumadin) for TWO weeks and direct thrombin inhibitors for ONE week.

If the patient is known to be either a LA or APA, a free Protein S level is a more accurate assessment.
Methodology:
Activity by optical density clot detection.
CPT Code:
85306