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HelpTest Code TOBRA Tobramycin, Random, Serum
Method Name
Immunoassay
Specimen Type
SerumOrdering Guidance
Serum for a peak level should be drawn 30 to 60 minutes after last dose (order TOBPA / Tobramycin, Peak, Serum).
Serum for a trough level should be drawn no more than 30 minutes before next scheduled dose (order TOBTA / Tobramycin, Trough, Serum).
Specimen Required
Preferred: Serum gel
Acceptable: Red top
Specimen Volume: 0.5 mL
Collection Instructions:
1. Serum gel tubes should be centrifuged within 2 hours of collection.
2. Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.
Specimen Minimum Volume
0.25 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 7 days |
| Frozen | 28 days | |
| Ambient | 72 hours |
Reject Due To
| Gross hemolysis | Reject |
Clinical Information
Tobramycin is an antibiotic used to treat life-threatening blood infections by gram-negative bacilli, particularly Citrobacter freundii, Enterobacter (all species), Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Providencia stuartii, Pseudomonas aeruginosa, and Serratia. It is often used in combination with beta-lactam therapy.
A tobramycin minimum inhibitory concentration (MIC) of less than 4.0 mcg/mL is considered susceptible for gram-negative bacilli, while a MIC of greater than 8.0 mcg/mL is considered resistant.
Toxicities include ototoxicity and nephrotoxicity. This risk is enhanced in presence of other ototoxic or nephrotoxic drugs. Monitoring of serum levels, renal function, and symptoms consistent with ototoxicity is important. For longer durations of use, audiology and vestibular testing should be considered at baseline and periodically during therapy.
Reference Values
TOBRAMYCIN, PEAK
Therapeutic: 3.0-12.0 mcg/mL
Toxic: >12.0 mcg/mL
TOBRAMYCIN, TROUGH
Therapeutic: <2.0 mcg/mL
Toxic: >2.0 mcg/mL
Day(s) Performed
Monday through Sunday
Report Available
Same day/1 to 2 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
80200
Forms
If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.