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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 done to check how well it’s working or to monitor levels after treatment.

Quick summary

["Tobramycin levels help ensure safe and effective antibiotic dosing."]

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

Key facts at a glance

LOINC
31096-1
Short code
Tobramycin Rand EID SerPl-mCnc
Synonyms
Tobramycin Rand EID SerPl-mCnc
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 receiving tobramycin, a strong antibiotic used to treat serious bacterial infections. It helps track whether your body is absorbing the drug properly and if levels remain within safe ranges to avoid side effects.

What to Expect Before the Test

No special preparation is needed, but you may need to fast for 8–12 hours before the draw if instructed. Bring a list of all medications, including over-the-counter drugs and supplements, to share with your provider.

What Happens During the Test

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but the procedure usually takes just a few minutes. The blood sample is sent to a lab for analysis.

What the Results Mean

Results are compared to a reference range specific to tobramycin, which varies by lab and patient factors like kidney function. High levels may indicate the drug isn’t being processed well, while low levels could mean it’s not working effectively.

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.

◆Associated findings1

Short name

Tobramycin Level

Frequently asked questions

How often will I need this test?
This test is usually done every few days during treatment, especially if you have kidney problems or are receiving high doses. Your provider will schedule follow-ups based on your treatment plan and lab results.
What are typical side effects of tobramycin?
Common side effects include nausea, vomiting, or ear pain (if taken orally). Rare but serious side effects include kidney damage or nerve damage. Always report any unusual symptoms to your provider.
Can I drink water before the blood draw?
Yes, you can drink water unless your provider specifies otherwise. Avoid caffeine or alcohol before the test, as they may affect lab results.
  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