Subcutaneous Heparin is NOT Contraindicated Prior to Hemodialysis
Subcutaneous unfractionated heparin (UFH) is not contraindicated before hemodialysis and can be safely used, though it is generally less effective than intradialytic anticoagulation protocols. 1, 2
Key Clinical Context
The question appears to conflate two distinct uses of heparin in dialysis patients:
- Prophylactic subcutaneous heparin (for VTE prevention in hospitalized dialysis patients)
- Intradialytic anticoagulation (to prevent circuit clotting during the hemodialysis procedure itself)
Both uses are permissible, but understanding the distinction is critical for optimal patient management.
Prophylactic Subcutaneous Heparin in Dialysis Patients
VTE Prophylaxis Recommendations
All hospitalized dialysis patients without contraindications should receive pharmacologic VTE prophylaxis, with LMWH preferred over UFH when creatinine clearance permits. 3, 4
For severe renal impairment (CrCl <30 mL/min), UFH is actually the preferred agent over LMWH due to hepatic metabolism rather than renal clearance, making it safer in this population. 3, 4, 5, 6
Standard prophylactic dosing is UFH 5,000 units subcutaneously either twice or three times daily, with three-times-daily dosing showing superior efficacy in surgical patients but higher bleeding risk in medical patients. 3, 4
Safety Profile
UFH prophylaxis has demonstrated mortality reduction (7.8% vs 10.9%) and decreased DVT incidence (4% vs 26%) in critically ill patients, including those with renal failure. 4
The primary contraindication is heparin-induced thrombocytopenia (HIT), not the dialysis procedure itself. 3, 5
Subcutaneous Heparin for Intradialytic Anticoagulation
Clinical Evidence
Subcutaneous administration of heparin 1 hour before dialysis has been studied but is generally inadequate for maintaining circuit patency throughout a dialysis session. 7
A study found that 5,000 units subcutaneously 1 hour pre-dialysis either failed to sustain dialysis due to fibrin formation or allowed elevated coagulation markers, while 10,000 units subcutaneously could only sustain dialysis in 3 of 5 patients. 7
Intravenous heparin administration (bolus plus continuous infusion) is far superior for preventing circuit clotting during hemodialysis, as it maintains therapeutic heparin levels (≥0.5 IU/mL) throughout the procedure. 7
Current Standard Practice
UFH remains the most commonly used anticoagulant for the hemodialysis extracorporeal circuit in the United States, typically administered as an intravenous bolus at dialysis initiation followed by continuous or intermittent dosing. 8, 1
Weight-based protocols and low-dose protocols for high bleeding risk patients are both acceptable, with adjustments based on clinical signs of circuit clotting. 1
Special Considerations and Pitfalls
Absolute Contraindications
Active HIT or history of HIT requires alternative anticoagulation (argatroban, danaparoid, or citrate). 3, 5, 8
Active uncontrolled bleeding is a contraindication to any systemic anticoagulation. 1
High Bleeding Risk Patients
Low-dose heparin protocols (reduced total dose) are preferred over regional heparinization for patients at increased bleeding risk, as they show equal or lower bleeding complications (10% vs 19%). 2
Regional heparinization offers no clinical advantage and may increase bleeding risk. 2
Monitoring Considerations
Laboratory monitoring of heparin during routine hemodialysis is not indicated for most patients and has not been shown to improve outcomes. 9
Consider monitoring only in select cases: extremes of body weight, repeated circuit clotting, or recurrent bleeding episodes. 9
Practical Algorithm
For VTE prophylaxis in hospitalized dialysis patients:
- Check for HIT history or active HIT → If present, use fondaparinux or danaparoid 4, 5
- If CrCl <30 mL/min → Use UFH 5,000 units SC twice or three times daily 4, 6
- If CrCl ≥30 mL/min → Prefer LMWH (enoxaparin 40 mg SC daily) 3, 4
For intradialytic anticoagulation: