What is the recommended subcutaneous dose of Unfractionated Heparin (UFH) for a 50Kg adult?

Subcutaneous UFH Dosing for a 50kg Adult

For a 50kg adult requiring subcutaneous unfractionated heparin (UFH), the recommended therapeutic dose is 250 units/kg every 12 hours, which equals 12,500 units subcutaneously every 12 hours. 1, 2

Dosing Considerations for Therapeutic Anticoagulation

Weight-Based Dosing Approach

When administering therapeutic doses of subcutaneous UFH, weight-based dosing is essential for optimal outcomes:

• Initial loading dose: 333 units/kg SC (16,650 units for a 50kg patient)
• Maintenance dose: 250 units/kg SC every 12 hours (12,500 units for a 50kg patient) 2

This regimen has been shown to be as effective and safe as low-molecular-weight heparin for treatment of venous thromboembolism and can be administered in both inpatient and outpatient settings 2.

Alternative Dosing Regimen

The 2024 NCCN Guidelines for Cancer-Associated Venous Thromboembolic Disease provide an alternative subcutaneous dosing option:

• Initial loading dose: 333 units/kg SC
• Followed by 250 units/kg SC every 12 hours 1

Prophylactic Dosing

If UFH is being used for VTE prophylaxis rather than therapeutic anticoagulation:

• Standard prophylactic dose: 5,000 units SC every 8-12 hours 1, 3
• For high-risk surgical patients: 5,000 units SC 2 hours before surgery and every 8-12 hours thereafter 3

Monitoring Recommendations

For therapeutic subcutaneous UFH:

• Monitor activated partial thromboplastin time (aPTT) 6 hours after morning injection
• Target aPTT: 1.5-2.0 times control (approximately 50-70 seconds) 1
• Monitor platelet count daily to detect potential heparin-induced thrombocytopenia 1
• Periodic hematocrit and tests for occult blood in stool are recommended 3

Special Considerations for 50kg Patients

• Lower weight patients may be at increased risk for bleeding complications with standard dosing
• For patients weighing <60kg, some guidelines recommend careful monitoring and potential dose adjustments 1
• Elderly patients (>60 years) may require lower doses of heparin 3

Common Pitfalls and Caveats

1. Avoid excessive dosing: Initial bolus doses >70 U/kg or total bolus >4000 U can increase bleeding risk 1

2. Administration technique: Use deep subcutaneous (intrafat) injection in the abdomen with a fine needle (25-26 gauge) to minimize tissue trauma 3

3. Injection site rotation: A different site should be used for each injection to prevent development of hematoma 3

4. Monitoring timing: For subcutaneous UFH, tests for adequacy of dosage are best performed on samples drawn 4-6 hours after injection 3

5. Transition to oral anticoagulants: When transitioning to warfarin, continue UFH for several days after the INR has reached the therapeutic range 3

By following these evidence-based recommendations, therapeutic anticoagulation can be safely and effectively achieved in a 50kg adult requiring subcutaneous UFH therapy.