PREVELANCE OF PRIMARY COAGULATION DEFICIENCIES IN PATIENTS WITH DEEP VENOUS THROMBOSIS

Hereditary causes of thrombosis are becoming more evident as assays (and antibodies) for antithrombin III, protein C, and protein S become more widely available. From March 1986 to January 1987, ninety-nine patients with venous thrombosis were referred to our laboratory for evaluation.This included 55 males and 42 females (age ranges:(1- 79 years). In 79 patients protein C antigens and activities were performed and 24 abnormally low values were obtained. Fourteen of these patients had multiple low values of other vitamin K dependent coagulation factors, reflecting warfarin therapy. Ten patients (12.7%) had isolated protein C deficiency with the other vitamin K dependent factors being within our normal ranges. Of 75 free protein S antigens performed there were 32 abnormally low values. Thirteen (17.3%) were isolated deficiencies. Of 62 antithrombin III antigens and activities measured, there were 8 (12.9%) abnormally low values. The prevelance of these hereditary deficiencies are higher in our referral population than previously reported. This may represent a true increase prevelance in our referral population or reflect a selection bias because of our careful screening of the patient́s history prior to performing the test, or an increased availability of the test to the clinicians. These test should be performed routinely in young patients with venous thrombosis and without predisposing risk factors. These results confirm that all patients with thrombosis should have a comprehensive evaluation done. Not only will the etiology be determined but given the cost of these evaluations, it is more efficient to profile rather than to order isolated request for one factor, as has often been the habit in the past