Practice Rational Testing

Monitoring aminoglycoside level

BMJ 2012; 345 doi: (Published 27 September 2012) Cite this as: BMJ 2012;345:e6354
  1. Suryabrata Banerjee, specialty registrar1,
  2. Manjusha Narayanan, consultant2,
  3. Kate Gould, professor3
  1. 1Queen Elizabeth Hospital, Gateshead NE9 6SX, UK
  2. 2Microbiology, Royal Victoria Infirmary, Newcastle Upon Tyne NE1 4LP, UK
  3. 3Microbiology, Freeman Hospital, Newcastle upon Tyne NE7 7DN
  1. Correspondence to: S Banerjee drsuryabrata{at}
  • Accepted 18 June 2012

Aminoglycosides are potent antibiotics, but monitoring of therapy is essential to ensure optimal treatment and prevent toxicity. This article reviews the available evidence for this evolving subject

Learning points

  • Monitoring of aminoglycoside therapy is essential to ensure optimal treatment and prevent toxicity

  • Aminoglycoside level monitoring can be done by several methods—trough level only, peak and trough level measurement, using nomograms, area under the curve methods, or bayesian systems

  • For patients with altered volume of distribution or creatinine clearance, monitoring frequency should be individualised as appropriate and expert help sought

  • Renal function should be monitored at the start of treatment and every 2-3 days thereafter (more frequently if unstable)

  • If aminoglycoside treatment is expected to continue >72 hours, patients should be informed of potential ototoxicity, and they should be assessed ideally at the start of treatment and then every week (in extreme cases every 2-3 days with a view to stopping treatment if toxicity develops)

A 48 year old woman admitted to hospital three weeks ago with a spontaneous intracerebral haemorrhage and right hemiparesis has developed high fever (39.8°C) associated with chills and rigors. She is tachycardic with a 30 mm Hg drop in systolic blood pressure to 100 mm Hg. She is feeling unwell and nauseous. On examination, her chest is clear, and the abdomen is soft except for a tender renal angle on the left side. She had a short term catheter inserted during this admission, which was last changed six days ago. A urine dipstick is positive for blood, protein, leucocytes, and nitrates.

A provisional diagnosis of acute pyelonephritis is made based on the clinical picture, and the patient is started on amoxicillin and once daily gentamicin after discussion with the microbiologist.

What is the next investigation?

General investigations

  • Full blood count, urea and electrolytes, C reactive protein—These are the baseline investigations, which are non-specific but …

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