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Test Code TOBR Tobramycin Level, Random

Additional Codes

EPIC LAB5326

Synonyms

  • Tobrex
  • Nebcin
  • Bethkis

Clinical Significance

Tobramycin is an aminoglycoside antibiotic used in the treatment of infections caused by Pseudomonas aeruginosa, Proteus species, E. coli, Klebsiella, Serratia, Citrobacter, Staphylococcus aureus, Enterobacter and other microorganisms.

 

Tobramycin’s toxic effect is produced by interfering with ribosomal protein synthesis. Tobramycin undergoes very little, if any, metabolization and is, therefore, eliminated as the parent drug by glomerular filtration. The half‑life of tobramycin in serum or plasma correlates closely with renal function and thus is quite variable between individuals and within one individual over time. Serum or plasma tobramycin concentration is also impacted by mode of administration, the volume of extracellular fluid, the duration of the treatment and physiological changes during the illness and therapy. The therapeutic range of tobramycin should be measured at peak as well as trough concentrations. In patients with pre‑existing renal damage or those to whom tobramycin has been administered for prolonged periods or in doses above the therapeutic range, hearing impairment and/or nephrotoxicity may develop. Therefore, monitoring of peak and trough tobramycin serum or plasma levels is critical in the prevention of these serious complications with the adjustment of dosage administration as indicated. 

 

Source: Roche Cobas TOBR2 Method Sheet Version 4.0 2024-07 

Methodology

Homogeneous enzyme immunoassay (Roche Cobas c503)

Sample Type

Preferred Sample Type
Light green top - Plasma

 

Acceptable Sample Type(s)
Dark green top - Plasma
Yellow top - Serum
Red top - Serum

Centrifuge: Yes

Specimen Minimum Volume

55 uL with insert cup

Specimen Stability

Temperature Time
Ambient (18-25°C) N/A
Refrigerated (4-8°C) (store) 3 days
Frozen (-15 to -20°C) 1 month*

Separate plasma or serum from cells within 2 hours.

NOTE: Stability limits only valid for capped specimens.

 

*Freeze only once!

Reference Ranges

Therapeutic Range
0.5 - 10.0 ug/mL

 

Critical Values
>12.0 ug/mL

 

Technical Range
0.4 - 12.0 ug/mL

Rejection Criteria

Hemolysis Index >800
Icterus Index >30
Lipemia Index >750, ultracentrifuge

Availability

Performed STAT
24/7 Yes

 

Performing Laboratory

MultiCare Yakima Memorial Hospital Laboratory

Lab Department

Chemistry

CPT Code

80200

LOINC

4058-4 Tobramycin random [Mass/Vol]