Pharmacokinetic Study of Fondaparinux in Outpatients With Renal Dysfunction

Inclusion Criteria: * Outpatients in the Medicine and Nephrology clinics who are 18 years or older, * Outpatients in the Medicine and Nephrology clinics who have an estimated creatinine clearances between 20-30ml/min, * Outpatients in the Medicine and Nephrology clinics who are able to give consent will be included. Exclusion Criteria: * anticoagulation therapy for thrombosis or other indication * pregnant or breast-feeding * hypersensitivity to fondaparinux * subjects also will be excluded if there is concern for an increased risk of bleeding which includes the following: * known bleeding disorder (see Section 8. Hemostatic Assessment) * blood transfusion in the past 3 months * acute ulcer disease with past 3 months * platelet count \< 120,000 mm3 * prolonged baseline prothrombin time (PT) or activated partial thromboplastin time (aPTT) above upper limit of normal laboratory range * major trauma or surgery within two weeks prior to enrollment * history of intracranial hemorrhage