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Gentamicin Serum/Plasma Mass Concentration (Quantitative)

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

This test measures the amount of gentamicin, a medication used to treat serious bacterial infections, in your blood serum or plasma.

Quick summary

["Helps ensure your antibiotic dose is safe and effective for your infection."]

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

Key facts at a glance

LOINC
31093-8
Short code
Gentamicin Rand EID SerPl-mCnc
Synonyms
Gentamicin 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 Matters

Gentamicin is a powerful antibiotic that can cause kidney damage if levels get too high. Your doctor may order this test to check how much of the drug is in your blood, especially if you’re taking it for a long time or have kidney problems.

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 you’re on a blood thinner, let your doctor know before the test.

What the Results Mean

Results help your doctor adjust your dose if needed. High levels may mean you need a lower dose, while very low levels might mean your infection isn’t fully treated. Your doctor will discuss these results with you.

Common Reasons for This Test

Doctors order this test if you’re taking gentamicin for a serious infection, have kidney issues, or if your doctor wants to monitor how well the drug is working in your body.

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

What happens if my gentamicin level is too high?
If your level is too high, it could cause side effects like nausea, vomiting, or kidney problems. Your doctor may lower your dose or switch to a different antibiotic to avoid these risks.
Why do I need this test if I only take gentamicin for a short time?
Even short-term use requires monitoring because gentamicin can build up in your body quickly. Your doctor wants to make sure you’re getting the right amount to fight the infection without harming your kidneys.
Can I eat or drink before this blood test?
You can eat and drink normally unless your doctor says otherwise. No fasting is required for this test.
  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