Heparin and heparin-like anticoagulants (unfractionated heparin (UFH), low molecular weight heparins (LMWH) and the pentasaccharide, fondaparinux) vary considerably in their glycosaminoglycan composition, specifically their average chain size (UFH > LMWH > fondaparinux). Even within the LMWH group there can be subtle differences in average chain size (tinzaparin > dalteparin > enoxaparin). These differences have important effects both on the antithrombin-mediated target specificity and dependence on renal clearance – smaller heparins having a higher anti-factor Xa: anti-factor IIa ratio and a greater dependence on renal clearance. The latter is very relevant when prescribing these agents, either at prophylactic or therapeutic doses, for patients with substantially reduced kidney function (CrCl<30mL/min) as observational data demonstrate clinically important increase in bleeding complications of anticoagulation in this group of patients. For this reason, in-patients in the NHS GGC renal unit with chronic kidney disease and CrCl <30mL/min do not routinely receive pharmaceutical thromboprophylaxis when admitted for non-operative reasons unless there are other risk factors for thrombosis.
Within NHS GGC the heparin agent of choice may vary between treatment and prophylaxis and for different indications – please consult NHS GGC Formulary or Therapeutics Handbook for preferred agent of choice. Based on relevant SPC guidance and limited additional literature the following recommendations are offered.
Note that this guideline is for adult non-pregnant patients only.