What is the recommended heparin (anticoagulant) regimen for patients undergoing dialysis?

Heparin Anticoagulation for Dialysis

Unfractionated heparin (UFH) is the standard anticoagulant for hemodialysis, administered as an initial bolus of 25-50 units/kg followed by continuous infusion of 500-1500 units/hour, or alternatively as 5000 units IV bolus followed by 1500-2000 units/hour infusion. 1, 2

Standard Heparin Regimens for Routine Hemodialysis

Preferred Approach: Continuous Infusion

• The FDA-approved regimen consists of 5000 units IV bolus followed by continuous infusion of 20,000-40,000 units over 24 hours (approximately 1500-2000 units/hour for a 4-hour dialysis session). 2
• The National Kidney Foundation identifies UFH as the anticoagulant of choice in severe renal insufficiency (creatinine clearance <30 mL/min) because it does not require dose adjustment for renal function. 3
• UFH is not cleared by dialysis and its metabolism is primarily hepatic, making it ideal for this population. 3, 1

Alternative Approach: Intermittent Bolus Dosing

• The FDA label describes intermittent IV injection as 10,000 units initial dose followed by 5,000-10,000 units every 4-6 hours. 2
• Research demonstrates that bolus heparin injection produces more effective anticoagulation than continuous infusion, with significantly higher PTT values (41.75±6.29 vs 37.90±4.77, p=0.036). 4
• However, bolus dosing creates immediate spikes in anticoagulant effect that increase bleeding risk in high-risk patients. 5

Monitoring Requirements

• Target aPTT should be 1.5 to 2.5 times the normal value, or whole blood clotting time elevated 2.5 to 3 times control. 2
• The American Society of Nephrology recommends monitoring aPTT at baseline, every 4 hours initially during continuous infusion, then at appropriate intervals. 3
• For intermittent dosing, perform coagulation tests before each injection during treatment initiation. 2
• Monitor platelet counts, hematocrit, and occult blood in stool throughout therapy regardless of administration route. 2

Modified Regimens for High Bleeding Risk

Low-Dose Heparin Protocol

• For patients at high bleeding risk, reduce the initial bolus and use lower maintenance infusion rates, targeting the minimum effective anticoagulation. 5, 6
• Research shows low-dose heparin (reduced from standard dosing) has lower bleeding complications (10%) compared to regional heparinization (19%, p<0.05). 6
• A tight heparin regimen of 15 IU/kg/hour has been successfully used in pediatric patients with bleeding risk, maintaining adequate PTT without complications. 7

Regional Citrate Anticoagulation

• Regional citrate anticoagulation is the preferred alternative for patients with high bleeding risk or heparin-induced thrombocytopenia (HIT). 1
• The American Society of Hematology recommends citrate regional over heparin in patients with subacute, remote, or past HIT requiring renal replacement therapy. 1

Low Molecular Weight Heparin (LMWH)

• LMWHs should be avoided or used with extreme caution in dialysis patients due to renal clearance and accumulation risk. 1
• If LMWH is used, the lowest effective dose is 125 anti-Xa units/kg as a single bolus, though this still carries accumulation risk. 8
• The National Comprehensive Cancer Network recommends avoiding standard LMWH doses in dialysis patients without anti-Xa monitoring due to severe bleeding risk from accumulation. 1
• Critical caveat: LMWHs are contraindicated when creatinine clearance <30 mL/min, with bleeding risk up to twice as high in severe renal impairment. 1

Special Situations

Heparin-Induced Thrombocytopenia (HIT)

• For acute HIT requiring dialysis, use argatroban as first-line alternative: 100 μg/kg bolus for continuous hemodialysis or 250 μg/kg for intermittent hemodialysis, followed by continuous infusion. 9, 3
• Argatroban is ideal because it lacks renal clearance and is not significantly removed by high-flux dialysis membranes. 1
• Danaparoid is an alternative with bolus dosing of 3750 units (2500 units if weight <55 kg) before the first two sessions, then 3000 units (2000 units if weight <55 kg) for subsequent sessions. 9, 3
• However, danaparoid accumulates in renal failure and is more difficult to use than argatroban. 9

Pediatric Dosing

• Use preservative-free heparin in neonates and infants. 2
• Initial dose: 75-100 units/kg IV bolus over 10 minutes. 2
• Maintenance infusion: 25-30 units/kg/hour for infants (infants <2 months require highest doses, averaging 28 units/kg/hour); 18-20 units/kg/hour for children >1 year. 2
• Adjust to maintain aPTT of 60-85 seconds. 2

Cardiovascular Surgery Patients on Dialysis

• Patients undergoing cardiopulmonary bypass require higher initial doses: minimum 150 units/kg, with 300 units/kg for procedures <60 minutes or 400 units/kg for procedures >60 minutes. 2

Common Pitfalls to Avoid

• Never use the 1 mL heparin vial intended for catheter lock flush for systemic anticoagulation during dialysis—this is a critical medication error. 2
• Avoid intramuscular heparin administration due to frequent hematoma formation. 2
• Do not assume regional heparinization is safer than low-dose systemic heparin—evidence shows equal or higher bleeding rates with regional techniques. 6
• Research demonstrates that maintaining plasma heparin levels ≥0.5 IU/mL is necessary to completely suppress coagulation activation and prevent fibrin formation during dialysis. 10
• Lower heparin levels may allow dialysis completion but permit ongoing fibrin generation and platelet activation, posing risks to both the procedure and patient. 10