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Test Code GENPK Gentamicin, Peak

Specimen and Container/Tube

Specimen Type: Serum

Preferred Specimen: Red Top

Other Acceptable specimens: Li Heparin Mint Green Top, Green Top Sodium Heparin, Lavendar K2 Top, Lavendar K3 Top

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

Collect specimen per standard collection procedure and send to laboratory immediately. 

 

Collect sample following standard collection methods 1 hour after completion of infusion of an intravenouse dose, or 2 hours after an intramuscular or oral dose of gentamicin.

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Collect sample following standard collection methods 1 hour after completion of infusion of an intravenouse dose, or 2 hours after an intramuscular or oral dose of gentamicin.
  • Samples should be centrifuged within 2 hours of collection.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature.
  • Aliquot sample into plastic transport tube containing a minimum of 0.2 mL of specimen.
  • Samples must be sent refrigerated at 2-8oC.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are clotted or grossly hemolyzed.
  • Specimens that were transported unspun/whole blood and draw time is greater than 6 hours.

Reference Values

Test

Age

Sex

Reference Range

Gentamicin

Extended Interval Dosing

All

All

 6 - 20 μg/mL

Gentamicin

Conventional Dosing

All

All

 3 - 10 μg/mL

Critical Values

Analyte

Unit

Low

High

Age

Gentamicin

μg/mL

N/A

>20.0

All

CPT Codes

N/A

LOINC Codes

3663-2

Volume

Preferred Volume: 0.5 mL

Minimum Volume: 0.2 mL

Specimen Stability

Storage Temperature

Stability

Room temperature

 N/A

Refrigerated

 1 week

Frozen

 1 month

Collection Instructions

Collect specimen per standard laboratory collection procedures. 

 

Collect sample following standard collection methods 1 hour after completion of infusion of an intravenouse dose, or 2 hours after an intramuscular or oral dose of gentamicin.

 

Test Components

Gentamicin
 

Clinical Indications

Measurements are used as an aid in the diagnosis and treatment of gentamicin overdose and in monitoring levels of gentamicin to ensure proper therapy.

Methodology

Homogeneous particle-enhanced turbidimetric immunoassay (Thermo Scientific)

Additional Information

  • Results should always be assessed in conjunction with patient's medical history, clinical examination and other findings.
  • Samples containing carbenicillin or piperacillin should be stored frozen if a delay in analysis of more than 8 hours is anticipated. Failure to freeze samples containing these antibiotics may result in falsely low gentamicin levels due to in vitro inactivation.
  • Sisomicin shows significant interference (> 50 %) with this assay.
  • High concentrations of penicillins or cephalosporins have been shown to inactivate gentamicin in vitro. The degree of inactivation is dependent on the particular aminoglycoside being measured, the type and concentration of the penicillin or cephalosporin that is also present, and the storage conditions of the sample. Samples from patients receiving additional antibiotics of these types should be assayed immediately or stored frozen.

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: 1 hour

Routine Turnaround Time: 4 hours

Testing Schedule: 24/7

Synonyms/Keyword Search

N/A

Last Review Date

1/26/23