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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Tobramycin

Test Code(s): TOBR / HCTOBR

CPT Code(s): 80200

Methodology: Particle Enhanced Turbidometric Inhibition Immunoassay (PETINIA)

Clinical Significance: Antibiotic

Days Performed: Daily, 24 hours.

Turnaround Time: Stat: 1 hour.
Routine: 4 hours.

Specimen Requirements

Specimen: Blood

Collection Instructions: Collect specimen for peak level 30 minutes after the end of a 30 or 60 minute infusion. Collect specimen for trough level 15 - 30 minutes prior to start of infusion.

Collection Container: Preferred: Red top
Also Acceptable: Green top (with lithium heparin anticoagulant)

Collection Volume: Preferred: 2 mL
Pediatrics: 0.4 mL

Sample Analyzed: Serum and plasma

Volume Required: Preferred: 1 mL
Pediatrics: 0.2 mL

Specimen Processing: Centrifuge immediately.  Transfer cell-free serum or plasma to plastic vial.  Freeze.

Specimen Transport: Transport specimen to UWHC Core Laboratory (B4/220) within 30  minutes.  Transport frozen serum on dry ice if coming from outreach location.

Unacceptable Criteria: Specimens collected in red cap with yellow ring (SST) or green cap with yellow ring (PST) tubes are not acceptable.
Specimens greater than 2 hours old, uncentrifuged when received by the laboratory, are not acceptable.

Stability: Ambient: 2 hours unspun; 8 hours spun
Refrigerated: 3 days
Frozen: 1 month


Interpretive Guidelines:

Optimal therapeutic range:

Peak: 5.0-10.0 mcg/mL

Trough: less than 2.0 mcg/mL

Test Limitations:

Patient samples which contain Kanamycin A, Kanamycin B, 3',4' dideoxykanamycin B will yield falsely elevated values for Tobramycin.

Critical Calls: View

Additional Information:

Result of "BELOW" indicates that the result is below the method detection limit of 0.3 mcg/mL. Tobramycin is an aminoglycoside antibiotic whose in-vitro activity is similar to that of gentamicin against gram-negative bacteria: it is more active than gentamicin against Pseudomonas aeruginosa. It also has activity against staphylococci.

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