What is the recommended subcutaneous (SQ) heparin (unfractionated heparin) dosing for an elderly patient with Deep Vein Thrombosis (DVT)?

Subcutaneous Heparin Dosing for DVT in Elderly Patients

For elderly patients with DVT, the recommended subcutaneous unfractionated heparin (UFH) dosing is 333 U/kg as an initial dose followed by 250 U/kg twice daily. 1

Recommended Anticoagulation Options for Elderly Patients with DVT

Unfractionated Heparin (UFH)

• Subcutaneous UFH dosing: 333 U/kg initial dose, then 250 U/kg twice daily 1
• Requires monitoring of aPTT with a target ratio of 1.5-2.5, corresponding to anti-factor Xa levels of 0.3-0.7 IU/mL 1
• Higher risk of heparin-induced thrombocytopenia (HIT) compared to LMWH, with risk as high as 5% 1
• Platelet count monitoring recommended every 2-3 days from day 4 to day 14 for patients with HIT risk ≥1% 1

Alternative Options (Preferred over UFH)

• Low-molecular-weight heparin (LMWH) is preferred over UFH for elderly patients with DVT (grade 2B recommendation) 1
• For elderly patients (>65 years), enoxaparin 30 mg subcutaneously every 12 hours is recommended 1
• In patients with renal failure, UFH 5000 U every 8 hours should be used 1

Special Considerations for Elderly Patients

• Elderly patients are at increased risk for both thrombosis and bleeding complications 2, 3

• Careful dose adjustment is necessary in patients with:

  • Renal impairment (common in elderly): Use caution with LMWH when CrCl <50 mL/min 1
  • Low body weight (<50 kg): Use caution with standard dosing 1
  • Obesity: Consider institutional weight-based dosing algorithms 1

• For elderly patients with severe renal impairment (CrCl <30 mL/min):

  • LMWH should be used with caution or avoided 1
  • If using LMWH, monitor anti-Xa levels (target 0.5-1.5 IU/mL) 1
  • UFH may be preferred in this population due to its shorter half-life and reversibility 1

Monitoring and Safety

• Monitor for signs of bleeding, the most significant complication of anticoagulation 1, 2
• For UFH, monitor platelet counts to detect HIT, especially in post-surgical patients 1
• LMWH has been shown to have fewer bleeding complications than UFH in elderly trauma patients 1
• LMWH is associated with lower mortality, fewer bleeding complications, and lower rates of DVT and PE compared to UFH in elderly patients 1

Duration of Treatment

• Anticoagulation should overlap with initiation of oral anticoagulants (if transitioning) for at least 5 days or until INR >2.0 for at least 24 hours 1
• Total duration of anticoagulation depends on underlying risk factors and should be determined based on individual patient assessment 1

Common Pitfalls to Avoid

• Underdosing elderly patients due to bleeding concerns can lead to treatment failure 2, 4
• Failing to adjust doses in renal impairment can lead to drug accumulation and bleeding 1
• Not monitoring for HIT when using UFH can miss this potentially serious complication 1
• Overlooking drug interactions with concomitant medications commonly used in elderly patients 1