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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, typically taken to monitor drug levels when prescribed for infections.

Quick summary

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

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

Key facts at a glance

LOINC
507-4
Short code
Tobramycin Islt MLC
Synonyms
Tobramycin Islt MLC
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
mlc
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 receiving tobramycin, a broad-spectrum antibiotic, to check if your blood levels are within the recommended range. This helps prevent toxic side effects while ensuring the medication works properly against your infection.

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 healthcare professional. The process is quick and typically painless.

What the Test Results Mean

Results are used to adjust your medication dose if needed. Low levels may indicate the antibiotic isn’t working well, while high levels could signal potential toxicity. Your provider will interpret these results in the context of your overall health and treatment plan.

Common Uses and Considerations

This test is most common in patients receiving intravenous tobramycin for serious infections like pneumonia, sepsis, or urinary tract infections. It’s especially important for those with kidney issues, as the drug is processed by the kidneys.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Tobramycin Level

Frequently asked questions

How often will I need this test?
The frequency depends on your treatment plan. Typically, it may be done several times during your course of therapy, especially if you have kidney problems or are receiving high doses.
What happens if my levels are too high?
If levels are too high, your doctor may adjust your dose, reduce the frequency of medication, or switch to a different antibiotic. Symptoms of toxicity are rare but can include nausea, hearing changes, or kidney issues—report any concerning symptoms to your provider.
Can I eat or drink before the test?
You can eat and drink normally before the test unless instructed otherwise by your healthcare provider. No fasting is required.
  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