Sample type: Serum
Test name: Gentamicin
Condition / Indication: Requesters have found these assays to be of value in all patients treated for >48 hours.
Advance warning: Not normally required during our core working hours (Mon – Fri 09:00 – 17:15). For samples originating outside of this trust, please contact the laboratory to discuss this assay being performed on Saturdays, Sundays and Bank Holidays when gentamicin samples can be assayed between 09:00 – 12:00.
Sample required: Approx. 1-2 mL of separated serum (minimum acceptable is 100µL). Samples may be sent by post. Transport time must be <4 weeks. Samples should be kept at 4°c if there is a delay in sending. Please contact laboratory if in doubt as sample integrity may be affected. Samples must be sealed and packed to conform to current regulations. Leaking samples may not be processed.
Timing of samples: We recommend a pre dose sample and a post dose sample, taken I hour after the end of iv/im administration.
Test information required: • Patient name, sex and age
• Laboratory number
• Dosage, frequency and timing of samples; especially important with once-daily dosing
• Clinical Summary
• Address for report
• Phone (fax if preferred) number for report or email address for an electronic copy
• Contact name
• Appropriate hazard warnings
Results: Results will be telephoned/faxed or emailed on the day of receipt for samples received between 9 am and 3 pm Monday to Friday and by 10.00 am on a Saturday. A written confirmation report will be sent by post.
Reference range: Once Daily
Pre dose <1 mg/L and Post dose >10 mg/L or 8 hour post (4.5 mg/kg) 1.5-6 mg/L or follow Hartford nomogram (but note this is for 7mg/kg)
Once Daily 5 mg/kg
Pre dose <2 mg/L but <1 mg/L after 3rd dose and post dose >8 mg/L
BD or TDS
Gm – pneumonia
Pre dose <2 mg/L
Post dose >7 mg/L
Infective endocarditis (IE)
Pre dose <1 mg/L
Post dose 3-5 mg/L
Container: Serum (Gold top)
Referred outside NBT for analysis? No
Discipline: Antimicrobial Reference Laboratory
Turnaround time: <1 day
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Re-assay interval: Once daily dosing - 6-8 days. BD or TDS dosing – 3-7 days – Assuming initial results are within expected range.