Lab Test

Tobramycin Level, Serum

Nebcin, TobraDex

Test Codes

LEVEL: Antrim #17515, EPIC: LAB5422, SOFT: TOBRA, PEAK: Antrim #17249, EPIC: LAB5423, SOFT: TOBRP, TROUGH: Antrim 17512, EPIC: LAB5424, SOFT: TOBRT, EID: (Is ONLY performed at Grosse Pointe, Royal Oak and Troy) Antrim #17512, EPIC: LAB5425, SOFT: TOBRD



Specimen Collection Criteria

Collect: One plain Red-top tube. (Minimum Whole Blood: 1.0 mL)

Do not use Serum Separator Tubes.
Time of Collection:
Consult Pharmacy Dosing Service.
Record the exact time of specimen collection on the tube or in the computer system.

Physician Office/Draw Specimen Preparation

Let specimens clot 30-60 minutes and refrigerate (2-8°C or 36-46°F) the collection tube within two hours of collection. (Minimum: 1.0 mL blood)

Preparation for Courier Transport

Transport: Collection tube, refrigerated (2-8°C or 36-46°F). (Minimum: 1.0 mL blood)

Rejection Criteria

  • Serum Separator (SST) tubes.
  • Severely lipemic or hemolyzed specimens. 

In-Lab Processing

Let specimens clot 30-60 minutes. Centrifuge specimen to separate serum from cells. Deliver an aliqout of serum orthe collection tube immediately to the appropriate testing station.


Specimen Stability for Testing:

Collection Tubes
Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 3 months

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days


Dearborn Chemistry Laboratory
Royal Oak Chemistry Laboratory


Sunday – Saturday, 24 hours a day.
STAT results available within 1 hour of receipt in the Laboratory.
Routine results available within 24 hours.

Reference Range

Conventional Dosing
Peak Levels: 5-10 mcg/mL.
Critical Levels: Greater than 12 mcg/mL.
Trough Levels: Less than 2 mcg/mL (Critical: Greater than 2.5 mcg/mL).
Once-A-Day Dosing Critical: Greater than 20 mcg/mL.

Test Methodology

Particle Enhanced Tubidimetric Inhibition Immunoassay.


Once-a-day aminoglycoside therapy will produce peak levels higher than critical values but not necessarily damaging to the kidneys. Individuals with impaired renal function will probably require a decrease in dose or an increase in their dosing interval.

Clinical Utility

Tobramycin is an aminoglycoside antibiotic. Tobramycin has a narrow therapeutic index which makes its use hazardous, especially in patients with impaired renal function. Accurate monitoring of the serum level in such patients is mandatory. This assay aids in the diagnosis and treatment of tobramycin overdose and in monitoring levels of tobramycin to ensure appropriate therapy.

CPT Codes

LOINC: 35670-9, 508-2, Peak 4057-6, EID 31096-1, Trough 4059-2


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