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Test Code 2539 Gentamicin, Peak, Plasma

Performing Laboratory

Barnes-Jewish Hospital Laboratory


Quantitative Microsphere System (QMS)

Testing Algorithm:

If the gentamicin value is a critical result , #1883 Potassium, Plasma will be performed, at an additional charge. 

Literature References:

Package Insert: Gentamicin GENT by Thermo Scientific 09/2014.

Specimen Requirements

Specimen Type: Plasma
Container/Tube: 1 mint green-top (lithium heparin) tube

Specimen Volume: Full tube
Collection Instructions: Draw blood 60 to 90 minutes after completion of drug infusion for intravenous dose.

Additional Information: Date and time of draw are required.

Day(s) Test Set Up

Monday through Sunday
Turnaround Time:
STAT: 1 hour after receipt in laboratory 
Routine: 2-4 hours after receipt in laboratory

Reference Values

Setting Target Range
Unspecified indication 3-10 mcg/mL
UTI/GPC synergy* 3-5 mcg/mL
Systemic illness 6-8 mcg/mL
Sepsis 8-10 mcg/mL
Physician alert value (automatic call-back)

≥21 mcg/mL

*UTI/GPC synergy refers to the synergistic effect of aminoglycosides with other antibiotics in treating urinary tract infections caused by gram-positive cocci (eg, Enterococcus).

Note: See Dosage Adjustment of Aminoglycoside Antibiotics Based on Drug Level Monitoring in Special Instructions.

Literature Reference:

Casabar E, BJH Antibiotic Utilization Review Subcommittee. Aminoglycoside dosing: Extended interval and traditional. BJH Pharmacy’s Toolbook (2005).

Test Classification and CPT Coding


84132-Potassium (if appropriate)

Additional Information

For BJH Laboratory Use Only
Alternate Tube:

1 dark green-top (lithium or sodium heparin) tube

1 red-top tube

1 lavender-top (EDTA) tube

Separator gel tube is acceptable but not preferred.

Analyte Stability:

Ambient: 8 hours

2° C to 8° C: ≤48 hours

≤-20° C: >48 hours

Laboratory Processing Instructions:

Test performed in BJH Core Lab.  Processed by automated line for delivery to the Cobas 8000. Completed specimens are stored refrigerated for 5 days.

Specimen Transport Temperature


LOINC Code Information

Name LOINC Code
Gentamicin, Peak, Plasma 3663-2