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Tobramycin

Clinical Biochemistry

Sample and container requirements

Serum

Minimum volume required

Special requirements

None

Patient preparation

See reference range for timing of sample collection.

Sample viability

Turnaround time

2 days

Reference range

Multiple Daily Dosing: Pre dose (trough) blood sample 15 mins before dose: <2 mg/L Post dose (peak) blood sample 1 hour after dose: 5 – 10 mg/L NB: ranges and comments DO NOT apply to renal patients Once Daily Dosing: Pre dose (trough): <1 mg/L For diagnostic purposes, the test findings should always be assessed in conjunction with the patient’s medical history, clinical examinations, and other findings.

Clinical guidance

Tobramycin is an aminoglycoside broad-spectrum antibiotic that is excreted by the kidneys. It is considered to be a TDM: if levels are too high, it can permanently damage the kidneys and hearing. Toxicity is principally related to a high pre-dose level, as the drug is not being excreted effectively and is accumulating in the body. Tobramycin is used almost exclusively in cystic fibrosis and bronchiectasis patients, generally on a single daily dosing regimen. Please refer to LabTestsOnlineUK to learn more about therapeutic drug monitoring (TDM). https://labtestsonline.org.uk/tests/therapeutic-drug-monitoring

Notes

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This information was last updated on 19 August 2026