Location out of bounds
Back to Test Catalog

Protein S Activity

Order Code: 1041

Test Information

This test provides the activity level of the blood coagulation factor, Protein S. This protein is one of the regulatory proteins in the blood clotting cascade.

Sample Requirements

Citrated Plasma (light blue top)

Additional Sample Requirements

Protein S activity is measured by a prothrombin-time-based clotting method. Patients should be off warfarin for at least 4 weeks before drawing a sample. The assay kit manufacturer has demonstrated the assay to be unaffected by levels of unfractionated heparin or low molecular weight heparin up to 2 IU/mL, but the results may be artifactually elevated in samples containing dabigatran or rivaroxaban. Platelet contamination of plasma samples causes an under-recovery of Protein S level, and proper sample preparation is required. Age and gender specific reference intervals are used.

Shipping Information


Requested Volume

0.5 ml

Minimum/Pediatric Volume

0.3 ml

CPT Codes




Turnaround Time

7 days


This website uses cookies to ensure you get the best experience on our website. Learn more