Antithrombin III, protein C, and protein S. Naturally occurring anticoagulant proteins

Arch Pathol Lab Med. 1988 Jan;112(1):28-36.


Protein C, protein S, and antithrombin III are naturally occurring anticoagulant proteins. Activated protein C and protein S act by inhibiting the action of the cofactors factor Va and factor VIIIa. Antithrombin III inhibits the serine proteases (factors II, IX, X, XI, and XII); its anticoagulant action is dramatically enhanced by heparin. Deficiencies of these proteins are associated with thromboembolic disease. Antigen and activity assays practical for the clinical laboratory are available for protein C and antithrombin III. Protein S antigen assays are also available. Diagnosis of an anticoagulant protein deficiency has serious implications for a patient and his kindred, and should therefore only be made on the basis of repeated abnormal determinations of a single protein in an individual patient, or documentation of the same protein deficiency in other family members.

Publication types

  • Review

MeSH terms

  • Antithrombin III / analysis
  • Antithrombin III / physiology*
  • Antithrombin III Deficiency
  • Blood Coagulation Disorders / diagnosis
  • Blood Coagulation Disorders / genetics
  • Blood Coagulation*
  • Glycoproteins / analysis
  • Glycoproteins / deficiency
  • Glycoproteins / physiology*
  • Humans
  • Methods
  • Protein C / analysis
  • Protein C / physiology*
  • Protein C Deficiency
  • Protein S


  • Glycoproteins
  • Protein C
  • Protein S
  • Antithrombin III