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Gentamicin (Serum/Plasma Mass Concentration)

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.

Quick summary

["Gentamicin levels help doctors monitor how much of this drug is in your blood to prevent harmful side effects."]

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

Key facts at a glance

LOINC
31091-2
Short code
Gentamicin Pk EID SerPl-mCnc
Synonyms
Gentamicin Pk EID SerPl-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
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 to treat infections like sepsis, bone/joint infections, or certain types of pneumonia. It helps ensure the drug is at the right dose to fight bacteria without causing kidney damage or other side effects.

What to Expect Before the Test

No special preparation is needed. A blood sample is taken from a vein in your arm. You may feel a small pinch, but it usually takes only a few seconds. If you’re on gentamicin, your provider may check levels more frequently during treatment.

What the Results Mean

Results show the concentration of gentamicin in your blood. Too much can harm your kidneys or nerves, while too little may not effectively treat your infection. Your provider will interpret these results in relation to your treatment plan.

Common Side Effects of Gentamicin

Gentamicin can cause side effects like nausea, vomiting, or hearing changes (rarely). If you experience dizziness, ringing in your ears, or signs of kidney problems (e.g., swelling, confusion), report them to your doctor immediately.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Gentamicin levels are critical for balancing treatment effectiveness and safety. Your provider will adjust your dose based on these results to prevent toxicity while ensuring the infection is fully treated.

Short name

Gentamicin Level

Frequently asked questions

Why do I need this test while on gentamicin?
This test helps your doctor monitor how your body is processing gentamicin. It ensures the drug stays at a safe level to fight infection without causing harm to your kidneys or nerves.
What happens if my gentamicin level is too high?
If levels are too high, it may lead to side effects like kidney damage or nerve problems. Your doctor will adjust your dose or temporarily stop the medication to lower the level.
Can I drink water before this test?
Yes, you can drink water as usual unless your doctor specifies otherwise. Avoid alcohol or caffeine before the blood draw, as they may affect test 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