Department of Pathology, University of Texas Southwestern Medical Center, Dallas 75235-9073, USA.
Protein C and S deficiency states predispose affected individuals to thrombosis, especially venous thrombosis of the lower extremities, usually beginning in the teenage years. Treatment of these patients is generally with oral anticoagulation, following initial heparinization. The classification of the deficiency states is dependent upon determination of the quantity and functional activity of either protein.