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Tobramycin Level (Serum or Plasma)

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

This test measures the amount of the antibiotic tobramycin in your blood. Tobramycin is used to treat serious bacterial infections, and your doctor may check this level to ensure it’s working properly and to avoid harmful side effects.

Quick summary

["Your doctor uses this test to monitor how well your body is responding to tobramycin treatment."]

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

Key facts at a glance

LOINC
25800-4
Short code
Tobramycin Islt SlowMyco
Synonyms
Tobramycin Islt SlowMyco
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
method-for-slow-growing-mycobacteria
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 Is This Test Done?

Your healthcare provider may order this test if you’re taking tobramycin to treat infections like pneumonia, urinary tract infections, or bloodstream infections. It helps ensure the correct dose is being used and prevents excessive levels that could cause kidney damage or other side effects.

How Is the Sample Collected?

A small needle will be inserted into your arm or vein to draw blood. You may feel a slight pinch, but it usually doesn’t cause much discomfort. The blood sample is then sent to a lab for testing.

What Do Results Mean?

Results are compared to a general reference range, but exact values can vary by lab. High levels may indicate too much antibiotic in your system, while low levels could mean the infection isn’t fully treated. Your doctor will discuss these results with you in detail.

Common Reasons for Testing

Doctors may check tobramycin levels if you’re on long-term therapy, have kidney problems, or if you’re experiencing side effects like nausea, dizziness, or hearing changes.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test is critical for managing antibiotic therapy safely. Tobramycin is potent, and monitoring helps balance effectiveness with potential risks, especially in patients with kidney issues or those taking other medications that interact with it.

Short name

Tobramycin Concentration

Frequently asked questions

What happens if my tobramycin level is too high?
A high level may mean you’re getting too much antibiotic, which could harm your kidneys or nerves. Your doctor might adjust your dose or stop the medication temporarily.
Can I eat or drink before this test?
You may eat and drink normally unless your doctor instructs otherwise. Some tests require fasting, but this one does not.
How long will I have to wait for my results?
Results are typically available within 1–3 business days, depending on your lab. Your doctor will contact you with the final report.
  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