Hereditary and acquired antithrombin deficiency.

Antithrombin (AT) is the most important inhibitor of activated coagulation enzymes. Deficiency of this protein can be a congenital defect. Different types have been described with a diminution of the entire molecule as well as diminution of activity only with normal concentration and normal activity and concentration but with a decreased sensitivity to heparin. There exist also different types of acquired deficiency due to a diminished production, an increased loss or an increased consumption of the inhibitor. Because AT deficiency is the cause of an increased thrombotic tendency in many cases the therapeutic and prophylactic possibilities are described. Since highly purified concentrates became available, substitution was attempted in cases of AT deficiency. It was found to be of greatest importance in cases of disseminated intravascular coagulation (DIC) which is a frequent consequence of septic or traumatic shock. In such cases an adequate AT-substitution can even be lifesaving as could be shown in different trials.