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Serum Gentamicin Concentration (Mass Concentration)

Published: August 9, 2026Updated: August 17, 2026

This test measures the amount of the antibiotic gentamicin in your blood serum. It helps doctors monitor how much of the drug is in your system to ensure proper dosing and avoid harmful side effects.

Quick summary

["Gentamicin levels help prevent overuse or toxicity from this antibiotic."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
47109-4
Short code
Gentamicin SerPl-sCnc
Synonyms
Gentamicin SerPl-sCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
17
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 Is This Test Done?

Your healthcare provider may order this test if you’re taking gentamicin (a medication used to treat serious bacterial infections) to check how well your body is handling the drug. It’s especially important for patients with kidney issues, as gentamicin can affect kidney function.

What Does the Test Involve?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed to measure the amount of gentamicin present.

What Are Common Results?

Results are typically reported in micrograms per milliliter (mcg/mL). Your doctor will compare these results to your specific dosing plan and kidney function to guide treatment.

What Are Possible Results?

Too-high levels of gentamicin can cause kidney damage, nerve problems, or hearing loss. Too-low levels may mean the infection isn’t fully treated. Your doctor will adjust your medication based on these findings.

Reference range

NCBI: NSE 0-17 ng/mLN/A

Specimen: serum

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Gentamicin Level

Frequently asked questions

Why do doctors check gentamicin levels regularly?
Doctors check gentamicin levels regularly to prevent overuse, which can harm your kidneys, nerves, or hearing, while ensuring the drug stays effective against infections.
How soon after starting gentamicin will I need this test?
You may need this test shortly after starting gentamicin (within 1–2 days) and then periodically, depending on your kidney function and how long you’re on the medication.
Can I eat or drink before this test?
You can eat and drink normally before the test, as it only involves a simple blood draw. However, always follow your doctor’s specific instructions.
  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 17, 2026. · Read our editorial policy