Heparin Dosing for Hemodialysis
Primary Recommendation
For routine hemodialysis anticoagulation, use unfractionated heparin with an initial bolus of 25-30 units/kg followed by a continuous infusion of 1,500-2,000 units/hour, as recommended by the FDA label. 1
Standard Dosing Protocol
Initial Bolus Dose
- Administer 25-30 units/kg as an initial bolus at the start of dialysis 1
- This loading dose places approximately 72% of patients within the therapeutic range (150-190 seconds whole blood aPTT) within 5 minutes 2
- Lower doses (20-25 units/kg) may be sufficient for many patients while still maintaining clear dialyzers 2
Maintenance Infusion
- Follow the bolus with continuous infusion at 1,500-2,000 units/hour throughout the dialysis session 1
- Continue infusion until 30 minutes before the end of dialysis to minimize post-dialysis bleeding risk 3
- Alternative approach: Some protocols use 15 units/kg/hour with sliding scale adjustments based on monitoring 2
Alternative Bolus-Only Method
- If continuous infusion is not feasible, administer 3,000 units as initial bolus, followed by 2,000 units at 2 hours 4
- This bolus method produces higher aPTT values (mean 41.75 seconds) compared to continuous infusion (37.90 seconds), which may be more effective for preventing circuit clotting 4
Monitoring Requirements
Coagulation Monitoring
- Target aPTT of 1.5 to 2.5 times normal value during dialysis 3
- For whole blood clotting time, target 2.5 to 3 times the control value 1
- Measure heparin concentrations in the dialyzer circuit: therapeutic range is 0.2-0.5 IU/mL 5
Platelet Monitoring
- Monitor platelet counts every 2-3 days from day 4 to day 14 to detect heparin-induced thrombocytopenia (HIT) 6
- Continue periodic platelet monitoring throughout the entire course of therapy 1
Critical Contraindications and Alternatives
When to Avoid Heparin
- Never use heparin in patients with history of HIT or active HIT 3, 1
- Avoid in patients with uncontrolled active bleeding (unless due to DIC) 1
Alternative Anticoagulants for HIT
When heparin is contraindicated due to HIT, use these alternatives:
Argatroban (preferred in renal failure):
- Bolus: 250 μg/kg for intermittent hemodialysis or 100 μg/kg for continuous hemodialysis 3
- Followed by continuous infusion adjusted to clinical response 3
- Optimal dosing may be as low as 5 mg bolus with 0.15 mg/kg/hour infusion based on aPTT monitoring 7
Danaparoid:
- Bolus: 3,750 units (2,500 units if weight <55 kg) before first two sessions 3
- Subsequent sessions: 3,000 units (2,000 units if weight <55 kg) 3
- Note: Danaparoid has prolonged half-life in renal failure, making argatroban preferable in this setting 8
Regional citrate anticoagulation:
- Can be used if equipment supports this technique 3
Regional Heparinization Techniques
For patients at high bleeding risk who cannot use alternative anticoagulants:
- High-dose regional heparinization: 120-144 IU/min with protamine neutralization maintains 0.4-0.6 IU/mL in the dialyzer and <0.2 IU/mL systemically 5
- Low-dose regional heparinization: 25 IU/min with neutralization maintains 0.15-0.35 IU/mL in the dialyzer and <0.15 IU/mL systemically 5
Key Advantages of Unfractionated Heparin
- No dose adjustment needed for renal function as metabolism is primarily hepatic 3
- Unfractionated heparin is the anticoagulant of choice in severe renal insufficiency (CrCl <30 mL/min) 3
- Rapid reversibility with protamine if bleeding occurs 1
Common Pitfalls to Avoid
- Never use heparin as a catheter lock flush product - use only dedicated catheter lock solutions 1
- Do not administer anticoagulants too close to neuraxial anesthesia due to spinal hematoma risk 6
- Avoid using the same injection site repeatedly for subcutaneous administration to prevent hematoma formation 1
- Be aware of high interindividual variability in heparin requirements - approximately 60% of patients remain in therapeutic range with standard protocols 2