Standardization of anticoagulant control.

Oral anticoagulant treatment is widely administered, particularly for the management and prophylaxis of thrombo-embolism. Anticoagulant dosage requires laboratory monitoring. An international system of standardization of laboratory control is necessary. A system based on the provision of a standardized tissue extract of thromboplastin (British Comparative Thromboplastin) is described. This is used in laboratories in seventy countries including a representative group of Italian hospitals and is now recommended as the international reference preparation.