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Test Code GENTP Gentamicin, Peak LAB28

Performing Laboratory

UnityPoint The Finley Hospital

Test Method

Homogeneous enzyme immunoassay; Roche cobas Pro

Performance

Testing is performed Monday through Sunday.

Routine: Typically completed within 4 hours after the specimen arrives at the testing site.

STAT: Typically completed within 1 hour after the specimen arrives at the testing site.

Specimen Requirement

  1. Lithium heparin plasma (green) is the specimen of choice.
  2. Serum (red) is also an acceptable sample type.
  3. It is recommended that the serum or plasma be separated from contact with cells within 2 hours from time of collection.
  4. Gentamicin specimens are stable refrigerated (2-8ºC) for 7 days, and frozen (-20ºC) for 4 weeks. Frozen specimens should be thawed only once.

Useful For

Gentamicin is an aminoglycoside antibiotic used in the treatment of infections caused by E. coli, Klebsiella, Enterobacter, Proteus mirabilis, Pseudomonas aeruginosa, Serratia, Staphylococcus aureus, Staphylococcus epidermidis and other microorganisms. Gentamicin’s toxic effect is produced by interfering with ribosomal protein synthesis. Gentamicin undergoes very little, if any, metabolization and is, therefore, eliminated as the parent drug by glomerular filtration. The therapeutic range should be measured at peak as well as trough concentrations. Peak serum or plasma concentrations of gentamicin are suggested to ensure that adequate antimicrobial activity is obtained. Trough gentamicin concentrations usually ensure that drug elimination is adequate and the drug concentration is above minimum inhibitory concentration. Serum or plasma gentamicin concentration is impacted by mode of administration, the volume of extracellular fluid, the duration of the treatment and physiological changes during the illness and therapy. Therefore, monitoring of peak and trough gentamicin serum or plasma levels is critical in the prevention of these serious complications with the adjustment of dosage administration as indicated.

Reference Values

5.0–8.0 μg/mL

Toxic:

> 12.0 μg/mL

CPT Code Information

80170 Therapeutic Drug Levels; Gentamicin, peak

LOINC Code Information

3663-2 Gentamicin [Mass/Volume] In Serum Or Plasma-Peak