Gentamicin Trough Level

Therapeutic Drug Monitoring

Normal Reference Ranges

Adult

< 2.0 (Target dependent on dosing protocol) mcg/mL

Pediatric

< 1.0 mcg/mL

Clinical Significance

Monitors clearance of aminoglycoside. Elevated trough levels indicate accumulator toxicity risking irreversible vestibular/cochlear damage and acute tubular necrosis.

Causes of High

  • Renal impairment
  • Imminent nephrotoxicity/ototoxicity

Causes of Low

  • Normal finding (subtherapeutic does not apply to trough as target is trough clearance)