Anticoagulation in Renal Failure
Patients with chronic kidney disease (CKD) present a dilemma in that they are simultaneously prothrombotic and haemorrhagic. Special consideration should be given to anticoagulation in these patients given the relatively high risk of bleeding complications. If in doubt, treatment options should be discussed with the Haematology team.
Unfractionated Heparin (UFH)
For inpatients with significant renal impairment, unfractionated heparin (UFH) is often the treatment of choice for initiating anticoagulation, especially when bleeding risk is high. Guidance for initiating UFH infusion can be found in the NHS Lothian Antithrombotic Guide on the Intranet.
Low Molecular Weight Heparin (LMWH)
In instances where treatment with UFH is problematic, for example when there are difficulties with intravenous access or where the patient could otherwise be discharged from hospital, the use of sub-cutaneous low molecular weight heparins (LMWH) has become increasingly popular. Whilst there have previously been concerns regarding the accumulation of these agents in renal failure, this can be monitored by measurement of a LMWH assay. LMWHs are also now used in our unit for anticoagulation where warfarin is contraindicated, or for the purposes of bridging anti-coagulation.
LMWH on dialysis
LMWH is often given on haemodialysis in order to maintain patency of the dialysis circuit. We switched from using tinzaparin to dalteparin for this in September 2021. The dalteparin protocol is given here.
The use of LMWH for bridging is short term until INR is therapeutic which usually takes about 5 to 7 days. It is important to note that use of treatment dose LMWH for prolonged periods in renal impairment may lead to accumulation therefore increasing the risk of bleeding.Our current guidelines for bridging anticoagulation and re-starting warfarin can be found here.
Despite increasing use of LMWHs for anticoagulation, warfarin is still the treatment of choice for many patients with CKD, including those on haemodialysis. The guidelines for initiating warfarin therapy in these patients differs slightly, and so care should be taken when prescribing loading doses. Patients on haemodialysis who have achieved therapeutic anticoagulation usually continue to have an INR check once weekly. The responsibility for warfarin prescribing varies across the 3 dialysis units in NHS Lothian, and the local unit policy should be referred to appropriately (see links below).
Novel / Direct Oral Anticoagulants
The Novel / Direct Oral Anticoagulants (NOAC / DOAC) comprise of direct Factor Xa inhibitors (apixaban, rivaroxaban, darexaban and edoxaban) and direct thrombin inhibitors (dabigatran). Whilst some of these agents are licensced for use in for patients with a mild-moderate degree of renal impairment, they may require dose adjustment if eGFR is <30ml/min/m2 , and are generally not recommended when eGFR is <15ml/min/m2. Their use in advanced kidney disease is not recommended.
In situations where thrombotic risk is high but it is not possible to use heparins, alternative agents are required – treatment in these situations is usually directed by the Haematology team.
Heparin-Induced Thrombocytopenia (HIT) – where antibodies are formed against heparin when it is bound to platelet factor 4 (PF4) – is a condition which results in widespread platelet activation and is associated with a very high risk of arterial and venous thromboses. The 4T scoring system can be used to predict risk of HIT – the score is based upon severity of thrombocytopenia, timing of thrombocytopenia in relation to heparin use, presence of thrombosis, and presence of alternative explanation for thrombocytopenia. Because HIT is associated with a high risk of thrombosis, treatment comprises of formal anticoagulation. In NHS Lothian, this is usually with IV argatroban or oral warfarin. Often patients are commenced on IV argatroban whilst warfarin is initiated and a therapeutic INR achieved. Argatroban should only be initiated under specialist advice and requires close monitoring.
VTE Prophylaxis in Renal Failure
For patients with advanced CKD, including those on haemodialysis, we have a unit-specific policy for VTE prophylaxis. Please click here to view our current guidance.
Acknowledgements: Lorna Thomson, Mariana Dimova and Neil Turner were the main authors for this page; first published in November 2001. It was updated by Ashley Simpson in 2019. The last modified date is shown in the footer.