Guidelines for Dosing and Monitoring of Low-Molecular Weight Heparin (LMWH)

Contents

Short Term Monitoring Guidelines

  • Baseline PT/aPTT
  • Baseline hematocrit (then prn if bleeding is suspected or confirmed
  • Baseline platelet count, and q2-3 days during first 2 weeks of LMWH therapy
  • Baseline serum creatinine, and q7days, (then prn if change in renal function is suspected, or if bleeding is suspected or confirmed)

Long Term Monitoring Guidelines

Patient weight q1-3 months and adjust LMWH dose if needed
Platelet count q1-3 months
Hematocrit q1-3 months
Serum creatinine/CrCl q1-3 months (and PRN if change in renal function is suspected or if bleeding is suspected or confirmed) and adjust LMWH dose if needed
Trough antiXa level
  • q1-3 months if CrCl > 60mL/min
  • q1 month if CrCl <60mL/min
  • goal: <0.5 unitsl/mL (adjust LMWH dose or dosing interval if needed

Use in Pregnancy

  • 1st and 2nd Trimester
Patient weight q1 month and adjust LMWH dose if needed
Platelet count q1 month
Hematocrit q1 month
Serum creatinine/CrCl q1 month and adjust LMWH dose if needed
Trough antiXa level
  • q1-3 months if CrCl > 60mL/min
  • q1 month if CrCl <60mL/min
  • goal: <0.5 unitsl/mL (adjust LMWH dose or dosing interval if needed
  • 3rd Trimester
Patient weight q2 weeks
Platelet count q2 weeks
Hematocrit q2 weeks
Serum creatinine/CrCl q2 weeks and adjust LMWH dose if needed
Trough antiXa level
  • q1 month if CrCl > 60mL/min
  • q2 weeks if CrCl <60mL/min
  • goal: <0.5 unitsl/mL (adjust LMWH dose or dosing interval if needed
Peak antiXa level
  • q2 weeks
  • check 4 hours after dose
  • goal 0.5-1 unit/mL (for q12h dosing of LMWH
  • Adjust LMWH dosing if needed, based on the table below
  • Peak antiXa Dosing Adjustments
Peak antiXa level (units/mL) Hold next dose Dosage change Next antiXa Level
<0.35 No Increase 25% 4hrs after next dose
0.35-0.49 No Increase 10% 4hrs after next dose
0.5-1 No None Next day, then within 1 week
1.1-1.5 No Decrease 20% Before next dose
1.6-2 For 3hrs Decrease 30% Before next dose and 4hrs after next dose
>2 Until antiXa level <0.5 Decrease 40% Before next dose and q12h until antiXa level <0.5 units/mL