"Pharmacokinetic Study of Fondaparinux in Inpatients With Renal Dysfunction"

Inclusion Criteria: * Inpatients who are 18 years or older * estimated creatinine clearances between 20-50 ml/min * current hospitalization for a cancer-related abdominal, breast surgery or elective orthopedic surgery * able to give informed consent * need for prophylactic anticoagulant therapy for increased risk of a thrombotic episode Exclusion Criteria: Use of the following * clopidogrel, aspirin, or NSAID usage,(usage is prohibited while patients are participating in the study) * body weight \< 50 kg * anticoagulation therapy for thrombosis or other indication * pregnant or breast-feeding * hypersensitivity to Arixtra® * thrombocytopenia associated with a positive in vitro test for anti-platelet antibody in the presence of Arixtra® * bacterial endocarditis * brain malignancy * increased risk of bleeding.