# A 75-year-old client weighing 60 kg has been on therapeutic enoxaparin 1 mg/kg subcutaneously every 12 hours for a recent DVT for 4 days. The peak anti-Xa level (drawn 4 hours after the morning dose) is 1.4 IU/mL; institutional therapeutic peak target for q12h dosing is 0.5-1.0 IU/mL. Creatinine clearance is 35 mL/min. Which action by the nurse is most appropriate?

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> language: en  
> subject: Adverse Effects/Contraindications/Interactions  
> category: PA

## Question

A 75-year-old client weighing 60 kg has been on therapeutic enoxaparin 1 mg/kg subcutaneously every 12 hours for a recent DVT for 4 days. The peak anti-Xa level (drawn 4 hours after the morning dose) is 1.4 IU/mL; institutional therapeutic peak target for q12h dosing is 0.5-1.0 IU/mL. Creatinine clearance is 35 mL/min. Which action by the nurse is most appropriate?

## Option

1. Administer a once-daily increased dose of enoxaparin 1.5 mg/kg subcutaneously because the high anti-Xa indicates suboptimal anticoagulation and the patient's recent deep vein thrombosis requires more aggressive management to prevent extension or embolism.
2. Hold the next dose and notify the provider; an anti-Xa of 1.4 IU/mL with the patients age (≥75), weight ≤60 kg, and CrCl **✔ Correct answer**
3. Continue the enoxaparin at 1 mg/kg every 12 hours because the anti-Xa level of 1.4 IU/mL reflects effective anticoagulation, and the patient is not bleeding, so no dose adjustment is needed despite the mild renal impairment.
4. Discontinue enoxaparin and give a bolus of unfractionated heparin (80 units/kg) followed by a continuous infusion, because the elevated anti-Xa indicates the need for a more readily reversible anticoagulant that can be monitored with aPTT.

**Correct answer: 2**

## Explanation

Anti-Xa interpretation — supratherapeutic LMWH
Anti-Xa level monitoring is recommended for LMWH in patients with renal impairment, obesity, pregnancy, extremes of age, or unexpected bleeding/clotting. Therapeutic peak (drawn 4 hours after SC dose):
• Treatment q12h dosing: 0.5-1.0 IU/mL.
• Treatment q24h dosing: 1.0-2.0 IU/mL.
• Prophylaxis: 0.2-0.5 IU/mL.

This client has 1.4 IU/mL at q12h dosing — supratherapeutic. Risk factors for accumulation are present (age ≥75, weight ≤60 kg, CrCl

## In-depth explanation

Clinical reasoning summary
Anti-Xa interpretation — supratherapeutic LMWH
Anti-Xa level monitoring is recommended for LMWH in patients with renal impairment, obesity, pregnancy, extremes of age, or unexpected bleeding/clotting. Therapeutic peak (drawn 4 hours after SC dose):
• Treatment q12h dosing: 0.5-1.0 IU/mL.
• Treatment q24h dosing: 1.0-2.0 IU/mL.
• Prophylaxis: 0.2-0.5 IU/mL.

This client has 1.4 IU/mL at q12h dosing — supratherapeutic. Risk factors for accumulation are present (age ≥75, weight ≤60 kg, CrCl

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