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Gentamicin (Serum/Plasma Concentration)

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 much of the drug is in your system to ensure it’s working safely.

Quick summary

["Gentamicin levels help prevent dangerous side effects from too much antibiotic in your blood."]

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

Key facts at a glance

LOINC
73365-9
Short code
Gentamicin ind plt IgG SerPl Ql FC
Synonyms
Gentamicin ind plt IgG SerPl Ql FC
Category
hematology
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
82784
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 those caused by bacteria like *Pseudomonas* or *Staphylococcus*. It helps track whether the dose is appropriate and whether the drug is working effectively. Too much gentamicin can harm your kidneys or nerves, so monitoring is crucial.

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 the concentration of gentamicin. The test doesn’t require fasting or special preparation.

What Are Common Results?

Results are typically reported as a concentration value (e.g., micrograms per milliliter). Your doctor will compare this to your specific dose and medical needs to determine if it’s safe and effective.

What Are Possible Side Effects?

High levels of gentamicin can cause side effects like nausea, dizziness, or kidney problems. Rarely, it may affect your hearing or nerves. Your doctor will adjust your treatment if levels are too high.

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 while I’m on this antibiotic?
Gentamicin is a narrow-spectrum antibiotic that can build up in your body quickly. Regular checks ensure your dose stays within safe limits to avoid kidney damage or nerve toxicity while still fighting infections.
What if my test results are higher than expected?
If levels are too high, your doctor may reduce your dose, switch to a different antibiotic, or adjust how often you take it. This helps protect your kidneys and nerves while keeping the infection under control.
Can I eat or drink before this test?
No special preparation is needed. You can eat, drink water, and go about your normal activities before the blood draw.
  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