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Gentamicin Concentration in Serum/Plasma

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

This test measures the amount of gentamicin, a type of antibiotic, in your blood. It helps doctors monitor how well your body is handling this medication.

Quick summary

["Gentamicin levels help ensure safe dosing and prevent potential kidney or nerve damage."]

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

Key facts at a glance

LOINC
88111-0
Short code
Gentamicin Rand EID SerPl-sCnc
Synonyms
Gentamicin Rand EID SerPl-sCnc
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 Is This Test Done?

Your doctor may order this test if you’re taking gentamicin to treat serious infections, such as bloodstream infections, pneumonia, or severe skin or bone infections. It helps track how much of the drug is in your blood to avoid harmful side effects.

What Does the Test Involve?

A blood sample is taken from a vein in your arm. The sample is sent to a lab where it’s analyzed to measure gentamicin concentration using a specialized immunoassay or similar method.

What to Expect Before the Test

No special preparation is needed, but inform your doctor about any medications, supplements, or recent illnesses that could affect results.

What to Expect After the Test

You may feel slight discomfort or bruising at the injection site, but this usually fades quickly. Avoid heavy lifting or strenuous activity for a few hours afterward.

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

Gentamicin Level

Frequently asked questions

How often will I need this test?
Your doctor will determine the timing based on your treatment plan. Typically, it’s done 30 minutes to 2 hours after a dose, then at intervals to check levels over time.
What if my results are outside the normal range?
If levels are too high, your doctor may adjust your dose or switch medications. If levels are too low, they may increase your dose or extend treatment duration.
Can I drink alcohol before this test?
No, avoid alcohol for 24 hours before the test, as it may interfere with lab results or affect how your body processes gentamicin.
  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