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26206 Tobramycin, Random, Serum (TOBRA)

Tobramycin, Random, Serum (TOBRA)
Test Code: TOBRASO
Synonyms/Keywords

​Antibiotic Assay
Antimicrobial Assay
Nebcin (Tobramycin Sulfate Injection)
Tobramycin, Random, Serum

Useful For

​Monitoring adequacy of serum concentration during tobramycin therapy

This unit code is used whenever a specimen is submitted or collected without collection timing information. The phlebotomist should use this unit code if she or he does not know if this is a peak or trough specimen.

Specimen Requirements
Specimen TypePreferred Container/TubeAcceptable Container/TubeSpecimen VolumeSpecimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​Serum​Serum Separator Tube (SST)​Red Top Tube (RTT)​0.5 mL​0.25 mL
Collection Processing 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 Stability Information
Specimen TypeTemperatureTime
​Serum ​ ​​Refrigerated (preferred)​7 days
​Frozen​28 days
​Ambient​72 hours
Rejection Criteria
Gross Hemolysis
Performing Laboratory Information
Performing LocationDay(s) Test PerformedAnalytical TimeMethodology/Instrumentation
​Mayo Clinic Laboratories​Monday through Sunday​1-2 days​Immunoassay
Reference Lab
Test 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 Range Information
Performing LocationReference Range
​Mayo Clinic Laboratories

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

 

Interpretation

​Target peak concentrations depend on the type of infection being treated. Goal trough levels should be below 2.0 mcg/mL. Concentrations refer to conventional (non-pulse) dosing. Prolonged exposure to either peak levels exceeding 12.0 mcg/mL or trough levels exceeding 2.0 mcg/mL may lead to toxicity.

Outreach CPTs
CPTModifier
(if needed)
QuantityDescriptionComments
​80200​1
Synonyms/Keywords

​Antibiotic Assay
Antimicrobial Assay
Nebcin (Tobramycin Sulfate Injection)
Tobramycin, Random, Serum

Ordering Applications
Ordering ApplicationDescription
​COM​Tobramycin, Random, Serum
​Cerner​Tobramycin, Random, S (TOBRA)
​Centricity​Tobramycin, Random, S (TOBRA)
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Specimen TypePreferred Container/TubeAcceptable Container/TubeSpecimen VolumeSpecimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
​Serum​Serum Separator Tube (SST)​Red Top Tube (RTT)​0.5 mL​0.25 mL
Collection Processing

​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 Stability Information
Specimen TypeTemperatureTime
​Serum ​ ​​Refrigerated (preferred)​7 days
​Frozen​28 days
​Ambient​72 hours
Rejection Criteria
Gross Hemolysis
Useful For

​Monitoring adequacy of serum concentration during tobramycin therapy

This unit code is used whenever a specimen is submitted or collected without collection timing information. The phlebotomist should use this unit code if she or he does not know if this is a peak or trough specimen.

Reference Range Information
Performing LocationReference Range
​Mayo Clinic Laboratories

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

 

Interpretation

​Target peak concentrations depend on the type of infection being treated. Goal trough levels should be below 2.0 mcg/mL. Concentrations refer to conventional (non-pulse) dosing. Prolonged exposure to either peak levels exceeding 12.0 mcg/mL or trough levels exceeding 2.0 mcg/mL may lead to toxicity.

For more information visit:
Performing Laboratory Information
Performing LocationDay(s) Test PerformedAnalytical TimeMethodology/Instrumentation
​Mayo Clinic Laboratories​Monday through Sunday​1-2 days​Immunoassay
Reference Lab
For billing questions, see Contacts
Outreach CPTs
CPTModifier
(if needed)
QuantityDescriptionComments
​80200​1
For most current information refer to the Marshfield Laboratory online reference manual.