Gentamicin

Clinical Biochemistry

All patients receiving gentamicin must have levels monitored, primarily to avoid renal toxicity, therefore renal function should also be regularly monitored.
For most patients requiring a gentamicin course, a once daily dosing regime can be used. Please refer to the Once Daily Gentamicin Policy Summary for more information on this regime.
Gentamicin levels can be taken at any time of day but the collection time should be convenient for the patient and for the testing laboratory – sampling and testing between 12 midnight and 6 am should be avoided.
Most gentamicin levels are a planned, non-urgent investigation.
Gentamicin levels are performed both at CGH and GRH Clinical Biochemistry – please send requests using Chemistry request forms to avoid delays in sample receipt and analysis.

Please refer to the Antibiotic Guidelines Page for information regarding patient preparation.

Samples must NOT be taken via lines

For adults, blood taken into a 5mL gold top gel tube (or rust top for the Acute Unit)

For children, blood taken into a 3.5mL rust top tube

Do not store. Send at ambient temperature to the laboratory as soon as possible.

The assays are run throughout the day and night. The in-lab turnaround time is less than 6 hours. Results are made available as soon as they are technically approved. Additional comments may be added later by the Consultant Microbiologist when results are clinically approved.
The test can be ordered as an urgent investigation.

Please refer to the Antibiotic Guidelines Page for information regarding therapeutic ranges.

If there is any doubt regarding interpretation, or a dose change needs to be discussed, contact the Consultant Microbiologist.

If you need advice please contact the duty consultant microbiologist or ward pharmacist.

Page last updated: 17/12/2025 | Page last reviewed: 17/12/2025