Dalteparin and other low-molecular-weight heparins are frequently used for the treatment of
deep vein thrombosis and for other indications. Unlike
unfractionated heparin (UFH),
dalteparin is mainly cleared through the kidney; therefore, it can accumulate in patients with impaired renal function, increasing the risk of
hemorrhage. An 84-year-old woman with
chronic renal failure was hospitalized because of
stenosis of a femorofibular bypass in her right leg. Peripheral transluminal angioplasty was performed successfully. Later the same day, Doppler sonography revealed
deep vein thrombosis of the left lower leg. Treatment with
dalteparin was started. The patient was discharged home 3 days later, with
dalteparin to be continued at home. One day later, the patient was rehospitalized because of a pronounced
hematoma on her flank. Her
hemoglobin level had dropped to 5.5 g/dl. Treatment with
dalteparin was stopped, and
protamine 2500 U and two transfusions of packed red blood cells were administered. Treatment with UFH and oral
anticoagulants were started because of a persistent risk for
venous thrombosis. Thereafter, the patient's
hemoglobin level remained stable, and no further
bleeding episodes occurred. As long as systematic studies of the efficacy and safety of
dalteparin in patients with severe renal impairment are lacking,
dalteparin should be avoided or used only with close monitoring of antifactor Xa activity in these patients. As an alternative, UFH can be used because monitoring of UFH is well established and easier than it is with
dalteparin. Renal impairment does not notably influence the short elimination half-life of UFH, which unlike that of
dalteparin or other low-molecular-weight heparins allows for rapid dosage adjustments to prevent
hemorrhage.