Antithrombin and heparin antithrombin patterns in pre-thrombosis and thrombosis.

An antithrombin assay (AA) and an antithrombin assay modified by the addition of heparin (H-AA) were performed using sera from healthy subjects, patients predisposed to thrombosis, and patients with thromboembolic disease. Characteristic AA, and H-AA patterns were found in each group. Normal controls and four of 39 "pill" patients (10%) had normal AA and H-AA findings (Pattern A). Normal AA, with "decreasing" H-AA (Pattern B) was found in sera of 31 of 39 "pill" patients (80%) and three patients who had non-embolic arterial occlusive disease. Low AA and "decreasing" H-AA (Pattern C) occurred in sera of four "pill"-takers (10%) and one patient who had an arterial embolus. Low AA and low H-AA (Pattern D) developed in sera of eight patients with thrombophlebitis and seven patients with pulmonary embolus. It is concluded that the AA and H-AA assays help to identify thrombosis-prone (Pattern C) and thrombotic (Pattern D) individuals for whom antiplatelet (aspirin; dipyridamole) or anticoagulant therapy might be beneficial.