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Tobramycin Concentration (Serum or Plasma)

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

This test measures the amount of the antibiotic tobramycin in your blood or plasma. Tobramycin is used to treat serious bacterial infections, often in patients with kidney issues or those who cannot tolerate other antibiotics.

Quick summary

["Tobramycin levels help doctors monitor your response to treatment and prevent dangerous drug buildup."]

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

Key facts at a glance

LOINC
508-2
Short code
Tobramycin Islt MIC
Synonyms
Tobramycin Islt MIC
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
mic
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 doctor may order this test if you’re taking tobramycin to treat infections like pneumonia, urinary tract infections, or bloodstream infections. It helps ensure the drug is at the right dose to fight bacteria without causing harm to your kidneys or other organs.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or vein to draw blood. If testing urine is involved, you’ll collect a sample in a clean container. Always follow your healthcare provider’s instructions for specimen collection.

What the Test Results Mean

Results show the concentration of tobramycin in your blood or plasma. High levels may indicate the drug isn’t being cleared properly, while very low levels might mean the infection isn’t responding. Your doctor will interpret these results in the context of your medical history and treatment plan.

Potential Side Effects or Risks

Tobramycin can cause side effects like nausea, kidney problems, or hearing changes. Rarely, it may lead to allergic reactions. If you experience severe symptoms (e.g., dizziness, swelling, or trouble breathing), seek medical attention immediately.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Tobramycin Level

Frequently asked questions

How often should I get this test?
Your doctor will determine the timing based on your treatment plan. Typically, levels are checked 1–2 hours after a dose to ensure safety and effectiveness. Follow-up tests may be scheduled during long-term antibiotic use.
Can I drink water before the blood draw?
Yes, you can drink water unless your doctor specifies otherwise. Hydration helps with blood circulation but doesn’t affect the test results.
What if my results are outside the normal range?
If results are abnormal, your doctor will adjust your treatment. High levels may require dose reductions or alternative medications, while low levels might mean your infection isn’t fully treated.
  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