Acquired factor X and antithrombin III deficiency in a patient with primary amyloidosis and nephrotic syndrome

A 45-year-old man with primary amyloidosis was initially seen with nephrotic syndrome. Factor X was found to be 5% and antithrombin III (AT III) 45% of normal plasma values. During an 11-month period, despite severe factor X deficiency, the patient did not have any bleeding complications. He developed progressive renal failure and AT III levels increased to normal, at which time he developed severe bleeding complications. These findings suggest a protective role of AT III deficiency against bleeding in a patient with severe factor X deficiency.