A client receives IV vancomycin 1 g every 12 hours for MRSA bacteremia. Before the next dose, the nurse reviews recent lab values. Which finding most concerns the nurse and warrants holding the dose plus notifying the provider?

1 Trough vancomycin level 12 mcg/mL
2 BUN 18 mg/dL
3 Trough vancomycin level 24 mcg/mL with serum creatinine increased from 0.8 to 1.6 mg/dL ✓ Correct answer
4 One episode of mild nausea

Explanation

Vancomycin nephrotoxicity is dose- and trough-dependent. A trough above 20 mcg/mL combined with a doubling of serum creatinine meets KDIGO criteria for acute kidney injury. The nurse must hold the dose and notify the provider for level review or dose modification. Trough 12 mcg/mL is sub-therapeutic but not nephrotoxic. BUN 18 mg/dL is within normal limits. Mild nausea is a common GI side effect that does not require holding.

In-depth explanation

Clinical Judgment Vancomycin requires therapeutic drug monitoring to balance efficacy and renal safety. Therapeutic trough for serious MRSA: 15-20 mcg/mL. Toxicity threshold: trough >20 mcg/mL with creatinine rise. Doubling of creatinine from baseline meets KDIGO Stage 1 AKI. Memory Tip Vanco trough >20 + creatinine doubled = HOLD and notify KR vs US US uses AUC/MIC monitoring (target 400-600) when available; trough 15-20 mcg/mL acceptable surrogate. Korean tertiary centers also adopt AUC monitoring; community hospitals still rely on trough.

Clinical scenario

Clinical Practice Guide 2020 IDSA / ASHP / SIDP / PIDS guidelines recommend AUC/MIC monitoring of vancomycin (target AUC 400-600 mg·h/L) for serious MRSA infection. Trough 15-20 mcg/mL remains an acceptable surrogate. Hold or adjust dose when trough exceeds 20 mcg/mL or creatinine rises >0.5 mg/dL above baseline. Caution Concurrent nephrotoxic drugs (aminoglycosides, NSAIDs, contrast dye, piperacillin-tazobactam) compound vancomycin renal injury. Always recheck creatinine every 48-72 hours during therapy.

Key concepts

Vancomycin trough — Serum vancomycin level drawn 30 minutes before the next scheduled dose. Therapeutic for serious MRSA: 15-20 mcg/mL. Above 20 mcg/mL: toxicity risk; recheck creatinine and consider dose adjustment.
Acute kidney injury (KDIGO) — KDIGO Stage 1 AKI: serum creatinine increase of 0.3 mg/dL within 48 hours OR 1.5 to 1.9 times baseline within 7 days, OR urine output <0.5 mL/kg/h for 6-12 hours. Doubling of creatinine = Stage 2.
Therapeutic drug monitoring (TDM) — Lab-guided dosing for narrow-therapeutic-index drugs. Required for vancomycin, aminoglycosides, lithium, digoxin, phenytoin, theophylline. Trough drawn 30 minutes pre-dose; peak drawn after distribution phase.

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For study reference only. Always follow current clinical guidelines and your institution’s protocols.

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A client receives IV vancomycin 1 g every 12 hours for MRSA bacteremia. Before the next dose, the nurse reviews recent lab values. Which finding most concerns the nurse and warrants holding the dose plus notifying the provider?

In-depth explanation

Clinical scenario

Key concepts

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