Is it best practice to administer heparin (unfractionated heparin) subcutaneously (subq) prior to dialysis?

Subcutaneous Heparin Prior to Dialysis is NOT Best Practice

No, it is not best practice to administer heparin subcutaneously prior to dialysis—intravenous administration during the dialysis procedure is the standard approach for anticoagulation. 1, 2

Standard Heparin Administration for Dialysis

The FDA-approved dosing for extracorporeal dialysis specifies 25 to 30 units/kg IV bolus followed by an infusion rate of 1,500 to 2,000 units/hour based on pharmacodynamic data. 1 This intravenous approach is administered at the start of dialysis, not subcutaneously beforehand.

Why IV Administration is Superior

• Immediate anticoagulation is required at the moment blood enters the extracorporeal circuit to prevent clotting in the dialyzer and tubing. 2
• Subcutaneous heparin has delayed and unpredictable absorption, making it unsuitable for the acute anticoagulation needs of dialysis. 3
• Research demonstrates that subcutaneous heparin 5,000 units given 1 hour before dialysis was either unable to sustain dialysis due to excess fibrin formation or allowed elevated markers of coagulation activation (fibrinopeptide A and beta-thromboglobulin). 3
• Even 10,000 units subcutaneously could only sustain dialysis in 3 of 5 patients for 5 hours, with progressively increasing coagulation markers and fibrin formation in the extracorporeal circuit. 3

Evidence-Based Heparin Protocols for Dialysis

Standard Protocol (Most Patients)

• Administer 5,000 units IV bolus a few minutes before connecting the patient to the circuit to ensure adequate mixing with blood. 2
• Follow with continuous infusion of 1,500 units/hour throughout dialysis. 1, 3
• This regimen maintains plasma heparin levels ≥0.5 IU/mL, which completely suppresses fibrinopeptide A generation and prevents visible fibrin formation in the extracorporeal circulation. 3
• Stop the heparin infusion 30-60 minutes before the end of dialysis based on time needed for needle puncture sites to stop bleeding. 2

High Bleeding Risk Patients

For patients with active bleeding, recent surgery, or coagulopathy, three approaches exist:

• Low-dose heparin protocol: 2,500 units IV bolus plus 1,000 units/hour infusion, though this may allow some coagulation activation after 4-5 hours. 3
• Tight heparin control: Use thrombin clotting time to assess heparin sensitivity before dialysis and monitor levels during dialysis, which limited bleeding complications to 5% overall in high-risk patients. 4
• Heparin-free dialysis: Can be performed successfully with frequent saline flushes (every 15-30 minutes), though complete clotting occurs in approximately 5% of cases with average blood loss of 150 mL. 5

Low-dose systemic heparin is superior to regional heparinization in high-risk patients, with bleeding complications occurring in 10% versus 19% of dialyses respectively. 6

Critical Pitfalls to Avoid

• Never rely on subcutaneous heparin alone for dialysis anticoagulation, as it provides inadequate and delayed anticoagulation. 3
• Do not administer the IV bolus simultaneously with circuit connection—give it a few minutes beforehand to ensure thorough mixing with blood before extracorporeal circulation begins. 2
• Avoid using activated clotting time (ACT) alone for monitoring, as visual inspection of the dialyzer and clinical assessment of bleeding risk are equally important for routine outpatient hemodialysis. 2
• Do not continue heparin infusion until the end of dialysis in patients without high thrombotic risk, as this increases bleeding at needle sites. 2

Special Considerations

For patients requiring bridging anticoagulation around other procedures, subcutaneous heparin or low-molecular-weight heparin may be used between dialysis sessions, but this is distinct from intradialytic anticoagulation. 7 During the actual dialysis procedure itself, intravenous administration remains essential for adequate circuit anticoagulation.