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Tobramycin Concentration in Serum/Plasma

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of the antibiotic tobramycin in your blood, typically taken to monitor drug levels when prescribed for serious infections.

Quick summary

["Tobramycin levels help ensure safe and effective dosing for bacterial infections."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
22750-4
Short code
Tobramycin Rand SerPl-sCnc
Synonyms
Tobramycin Rand SerPl-sCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0.8
Ref high
1.2
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85610
SNOMED
396252006
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your healthcare provider may order this test if you’re taking tobramycin to treat infections caused by bacteria that are resistant to other antibiotics. It helps adjust your dose to avoid toxicity while maximizing effectiveness.

What to Expect Before the Test

No special preparation is needed. A blood sample is drawn from a vein, usually in your arm, by a trained healthcare professional.

How the Results Are Used

Results guide your doctor in determining whether your dose needs adjustment. High levels may indicate toxicity, while low levels may mean the infection isn’t fully treated.

Possible Side Effects or Risks

Tobramycin can cause side effects like nausea, kidney problems, or hearing issues. Rarely, it may affect your blood cells or cause allergic reactions.

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: serum

Inform your healthcare provider if you are taking blood thinners. No special preparation required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Tobramycin levels are critical for managing infections caused by Pseudomonas or other resistant bacteria. Proper monitoring prevents overuse (leading to resistance) or underuse (leading to infection recurrence).

Short name

Tobramycin Level

Frequently asked questions

What does a ‘normal’ result mean?
There’s no single ‘normal’ range for tobramycin because it varies based on dose, infection type, and individual health. Your doctor will compare your result to your specific treatment plan.
How often will I need this test?
Your doctor may schedule this test during or after your treatment course, depending on how your body responds. Follow-up tests could be weekly or monthly.
Can I eat or drink before the test?
Yes, you can eat and drink normally unless your doctor instructs otherwise. Avoiding food/drink may not be necessary for blood tests like this.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy