Low molecular weight heparins in renal failure.

Low molecular weight heparins are now commonly used for systemic anticoagulation. Although elimination is mainly by the renal route, these drugs are being prescribed to patients who are dialysis dependent or have renal failure. We report 3 cases where the use of these drugs in patients with severe renal failure significantly prolonged anti-Xa activity and serious bleeding complications occurred. Concomitant prescription of other anti-thrombotic drugs may have contributed to the bleeding in 2 cases. These cases emphasize the potential toxicity of low molecular weight heparins in patients with severe renal failure and that these drugs should be used with great caution in such patients. If prescribed, doses should be lowered and anti-Xa activity frequently measured. The use of other anti-thrombotic drugs should be minimized.