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Tobramycin Concentration in Serum or Plasma

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

This test measures the amount of the antibiotic tobramycin in your blood, often done to check how well it’s working to treat infections like pneumonia, urinary tract infections, or bloodstream infections caused by bacteria sensitive to this drug.

Quick summary

["Tobramycin levels help ensure you’re getting the right dose to fight infection without risking harmful side effects."]

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

Key facts at a glance

LOINC
56705-7
Short code
Tobramycin IgE Qn
Synonyms
Tobramycin IgE Qn
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 serious bacterial infections. It helps monitor your drug levels to prevent toxicity or insufficient treatment. Common reasons include managing infections in the lungs, kidneys, or bloodstream.

How the Test Works

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed using a method called immunoassay to measure the tobramycin concentration in your blood plasma or serum.

What to Expect Before the Test

No special preparation is needed, but inform your provider if you’re taking other medications or have allergies. Avoid eating or drinking anything for 8–12 hours before the test if instructed, though this is less common for blood draws.

What to Expect During the Test

You’ll lie down comfortably while a healthcare provider inserts a small needle into your vein. You may feel a slight pinch, but the procedure usually takes only a few minutes. You can resume normal activities immediately afterward.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Tobramycin Level

Frequently asked questions

How long does it take to get results?
Results are typically available within 24 to 48 hours, depending on your lab’s processing schedule. Your provider will contact you once they’re ready to discuss the findings.
What do my results mean?
Your results will show the concentration of tobramycin in your blood. Your provider will compare these numbers to your specific treatment plan and any reference ranges provided by your lab to determine if your dose needs adjustment. They’ll explain what the results mean in the context of your health.
Can I eat or drink before this test?
Generally, no fasting is required for this test, but follow your provider’s instructions if they specify any dietary restrictions. If you’re unsure, ask your lab or provider before the test.
  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