Hereditary deficiencies of protein S (PS) increase the risk of venous thrombosis; however, assessing the plasma levels of PS can be difficult because of its complex physiological interactions in plasma, sample-related preanalytical variables, and numerous acquired disease processes. Reliable laboratory assays are essential for accurate evaluation of PS when diagnosing a congenital deficiency based on the plasma phenotype alone. This report presents the current evidence-based recommendations for clinical PS assays as well as when to test for PS abnormalities.
Marlar RA, Gausman JN, Tsuda H, Rollins-Raval MA, Brinkman HJM. Recommendations for clinical laboratory testing for protein S deficiency: Communication from the SSC committee plasma coagulation inhibitors of the ISTH. J Thromb Haemost. 2021 Jan;19(1):68-74. doi: 10.1111/jth.15109. PMID: 33405382.