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HelpTest Code LAB1135 Tobramycin, Random, Plasma or Serum
Additional Codes
| Test Name in EPIC | EPIC Test Code | Mnemonic |
|---|---|---|
| TOBRA RANDOM | LAB1135 | TOBRR |
Useful For/Utility
The Tobramycin assay is used for the quantitative determination of tobramycin in human serum or plasma.
Methodology
Particle-Enhanced Turbidimetric Inhibition Immunoassay (PETINIA)
Clinical Information
Tobramycin sulfate is an aminoglycoside derived from Streptomyces tenebrarius. This aminoglycoside antibiotic is used to treat serious bacterial infections by inhibiting the growth of the bacterium by intervening in the protein synthesis thereby killing the bacterium. Tobramycin is absorbed minimally from the gastrointestinal tract. In the first 24 hours after intravenous dosing, the usual route of administration, about 99% of the tobramycin is excreted unchanged by the kidneys. The average half-life in patients with normal renal function is about 2 to 3 hours. Therapeutic serum levels vary depending on the microorganism involved and the patient’s tolerance to the drug. Tobramycin serum or plasma concentrations are monitored to help guide therapy, since individual patient differences require dose changes that are difficult to predict. Monitoring serum or plasma levels of tobramycin decreases the frequency of serious toxic effects.
Specimen Requirements
Loading Dose Kinetics:
1. Levels after a loading dose should be drawn 1 hour and 12 hours after infusion is complete, keeping in mind that draw times may vary depending on dose schedule planned.
2. Subsequent levels are subject to change based on the results of the 1st level and the patient’s kidney function.
3. The pharmacy will notify lab of any changes in time. Also, a creatinine will be ordered separately if needed.
4. For newborns and/or NICU babies, draw specimens according to the following schedule as ordered per physician:
| Dosage Schedule | Draw Time |
| Q 8 hours | 6 hours after infusion is complete |
| Q 12 hours | 8 hours after infusion is complete |
| Q 18 hours | 12 hours after infusion is complete |
| Q 24 hours | 12 hours after infusion is complete |
Specimen must be refrigerated until test is performed.
Submit only 1 of the following specimens:
Preferred:
Specimen Type: Plasma
Container/Tube: Light-green top (lithium heparin gel)
Specimen Volume: 1 mL
Specimen Minimum Volume: 0.5 mL/pediatric: 0.2 mL in a green-top MICROTAINER
Collection Instructions:
1. Draw level 8 hours after the END TIME of infusion. This will be used with 7 mg/kg or 5 mg/kg once daily dosing. If toxicity is suspected, draw level when ordered STAT.
2. Spin down, separate from cells and aliquot within 2 hours of draw.
Additional Information:
1. Avoid repeated freeze/thaw cycles.
2. Specimen should be analyzed in an appropriate period of time to assess dosing.
3. If extreme lipemia-use ultracentrifuged specimen.
4. Label specimen appropriately (plasma).
Alternate:
Specimen Type: Serum
Container/Tube: Serum gel
Specimen Volume: 1 mL
Specimen Minimum Volume: 0.5 mL/pediatric: 0.2 mL in a red-top MICROTAINER
Collection Instructions:
1. Draw level 8 hours after the END TIME of infusion. This will be used with 7 mg/kg or 5 mg/kg once daily dosing. If toxicity is suspected, draw level when ordered STAT.
2. Spin down, separate from cells and aliquot within 2 hours of draw.
Additional Information:
1. Avoid repeated freeze/thaw cycles.
2. Specimen should be analyzed in an appropriate period of time to assess dosing.
3. If extreme lipemia-use ultracentrifuged specimen.
4. Label specimen appropriately (serum).
Specimen Transport Temperature
Refrigerate 5 days if aliquoted/Frozen OK/Ambient 8 hours OK
Day(s) Test Set Up
Monday through Sunday
Performing Laboratory
Chemistry-
SMDC Clinical Lab
Fargo Hospital Lab
Test Classification and CPT Coding
80200
Reference Values
Therapeutic Range: 5.0-8.0 µg/mL
There are no established reference ranges for Tobramycin, Random.