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Test Code BLOD0535 Gentamicin, Random, Serum

Useful For

Antimicrobial drug monitoring


Particle-Enhanced Turbidimetric Inhibition Immunoassay (PETINIA)

Performing Laboratory

Bozeman Health Laboratory Services

Specimen Requirements

Specimen Type: Plasma or serum
Container/Tube: Light-green top (lithium heparin gel), red top, or gold top
Specimen Volume: 1 mL
Specimen Minimum Volume: 0.5 mL

Collection Instructions:

1. Draw blood 30 minutes after completion of infusion of an intravenous dose.

2. Spin down within 2 hours of draw and remove plasma or serum from cells.

3. Label specimen as plasma or serum and with time of draw.

4. If there is a delay in transport of >8 hours, refrigerate specimen, and send specimen refrigerated.

Additional Information: Draw time is only a recommendation. Specific circumstances related to an individual patient, eg, renal function, hepatic function, concurrent medications, signs or symptoms, and/or therapeutic response may necessitate individualization of drawing schedules.

Specimen Transport Temperature

Ambient <8 hours/Refrigerated >8 hours/Frozen

Specimen Stability


Specimen Type Temperature Time
Plasma or Serum Ambient 72 hours
  Refrigerated 14 days
  Frozen 28 days


Reference Values

Random:  No established reference range


Peak therapeutic concentration:                    4.0-10.0 ug/mL

Toxic concentration (automatic call-back):             >12.0 ug/mL


Trough therapeutic concentration:                   0.0-1.0 ug/mL

Toxic concentration (automatic call-back):               >2.0 ug/mL


Therapeutic gentamicin concentrations vary significantly depending on the individual patient. A range of 4.0 to 8.0 µg/mL (8.64-17.28 µmol/L) for peak drug levels indicates effective plasma or serum levels for many patients; however, some individuals are best treated at concentrations outside this range. Although it has not yet been established exactly what specimen concentration is toxic, minimal values in excess of 2 µg/mL (4.32 µmol/L) for longer than 10 days have been associated with toxicity. The physician must determine the most appropriate therapeutic range for each patient.

Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding