Vancomycin Trough Level
MOC local note
AUC-guided monitoring is guideline-preferred for serious MRSA where available. Not routinely available locally, so trough-based monitoring remains the practical workflow here. Follow local pharmacy protocol for dosing and adjustment.
before prescribing / checking a level
- review first: renal function, current dose and interval, trough timing
history
- infection: source, bacteremia, endocarditis, osteomyelitis, MRSA
- renal risk: AKI, CKD, dehydration, sepsis
- nephrotoxins: aminoglycosides, NSAIDs, contrast, others
examination
- infection: fever, hemodynamic status, treatment response
- renal: fluid status, urine output, volume depletion
dose
- loading 25 to 30 mg/kg (actual body weight) for serious infection / critical illness
- maintenance 15 to 20 mg/kg/dose, round to 250 mg, q8 to 12h (q8h if increased clearance, young, burns)
- max 2 g/dose unless trough is low
escalate now if
- sepsis or hemodynamic instability
- AKI or rising creatinine
- very high trough with worsening renal function
- suspected vancomycin toxicity
which level to send and when
- vancomycin trough, creatinine, U&E · CBC, CRP ± cultures
timing
- draw 30 min before the 4th dose
- if interval >24 h, draw before the 3rd dose
- never from the vancomycin line
- do not delay doses waiting for level (unless concerned)
how to interpret it
targets: guideline-preferred
- AUC24/MIC 400 to 600 mg·h/L for serious/invasive MRSA (assuming MIC 1 mg/L, broth microdilution)
- aim for target early, within 24 to 48 h
- AUC-guided dosing is more accurate and causes less nephrotoxicity than trough-guided dosing
targets: local practical (trough-based)
- standard trough 10 to 15 mg/L
- selected deep-seated infection 15 to 20 mg/L (endocarditis, bacteremia, osteomyelitis, severe pneumonia)
- use 15–20 selectively and watch renal function: main driver of vancomycin AKI
do not treat a trough as an AUC
- trough of 15 to 20 is not a universal surrogate for AUC 400 to 600
- 2009 surrogate approach, withdrawn: drove higher exposure and more nephrotoxicity
dose adjustment / next action
check before changing a dose
- the level: true trough? drawn immediately before next dose, not from vancomycin line
- the regimen: current dose, interval, doses given on time, right patient?
- the kidneys: creatinine trend, urine output; has renal function changed since the dose was calculated?
- the history: previous levels, concomitant nephrotoxins
- the infection: indication, source, culture/MIC if available, clinical response
then
- follow local pharmacy/institutional protocol
- do not act on an isolated or mistimed level: repeat it
renal function and toxicity monitoring
- RFTs q48 to 72h, daily if unstable or on other nephrotoxins
- recheck level after any dose change or renal function shift
adverse effects
- nephrotoxicity: the main concern; minimize concurrent nephrotoxins
- phlebitis (acidic pH): slower infusion, adequate dilution, central access
- flushing syndrome (histamine, erythematous rash of head/neck/trunk): infuse ≤500 mg/h (≥1 h), give antihistamine
when to hold / escalate: ID / pharmacy / microbiology
- rising creatinine
- persistently abnormal troughs
- suspected toxicity
- deep-seated infection not responding
MOC pearl
a correctly timed trough, drawn immediately before the next dose, matters more than the number itself.
evidence / local-protocol status
| source | type |
|---|---|
| ASHP / IDSA / PIDS / SIDP Revised Consensus Guideline for Therapeutic Monitoring of Vancomycin (2020) | international guideline |
| AUC-guided monitoring not routinely available locally; trough-based monitoring is the practical workflow here | Kuwait local protocol |
Verify indication, dose, allergies, interactions, renal/hepatic function and local protocols before prescribing.
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reviewed Aug 2026updated Sep 2026file lab/vancomycin-trough-level