PART of the fascination of medicine lies in the ever-increasing scientific knowledge on which its practice is based. There are times, however, when it is not clear whether the most recent enthusiasm has a practical application of benefit to the patient. The decision is particularly difficult when the application of theory to practice is based on superficially attractive, even elegant, extrapolation. The choice of method in the laboratory control of anticoagulant therapy is a case in point. It might be left for time to resolve the claims and counterclaims were it not that basic issues are involved which could jeopardize the proper use of anticoagulant therapy.
The physician responsible for a patient with thromboembolic disease should be aware of a number of interrelated aspects of anticoagulant therapy, particularly selection of the patient to be treated, the complications of therapy, and the method of laboratory control. This discussion will apply to