Skip to content

Levofloxacin concentration in serum/plasma (substance concentration)

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

This test measures the amount of the antibiotic levofloxacin in your blood. It helps your healthcare provider check if the drug is working properly and at the right level in your system.

Quick summary

["This test helps ensure your antibiotic is effective and avoids potential side effects."]

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

Key facts at a glance

LOINC
20629-2
Short code
levoFLOXacin Susc Islt
Synonyms
levoFLOXacin Susc Islt
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 doctor may order this test if you’re taking levofloxacin to treat or prevent bacterial infections. It helps monitor whether the drug is reaching the right amount in your bloodstream, especially if you have kidney issues or take other medications that could affect how levofloxacin works.

How Is the Sample Collected?

A blood sample is taken from a vein, usually in your arm. You may feel a small pinch when the needle goes in, but it usually doesn’t cause much discomfort afterward.

What Should You Expect Before the Test?

No special preparation is needed, but let your doctor know if you’re taking other medications, have kidney problems, or are pregnant. Avoid eating or drinking anything for a short time before the test if instructed.

What Are Possible Results?

Results are used to guide your treatment plan. Very high or very low levels may signal issues like poor absorption, kidney problems, or drug resistance. Your doctor will interpret these results in the context of your overall health and treatment.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Levofloxacin Level

Frequently asked questions

How Does This Test Help Healthcare Providers?
This test helps ensure levofloxacin is at an effective concentration to fight infections without causing harmful side effects. Low levels may mean the drug isn’t working well, while high levels could indicate kidney problems or improper dosing. It’s especially important for patients with kidney disease or those taking other medications that interact with antibiotics.
What If My Results Are Abnormal?
If your results are outside the expected range, your doctor may adjust your dose, change your treatment plan, or investigate other causes. They’ll discuss this with you and decide the best next steps based on your health.
How Often Will I Need This Test?
The frequency depends on your treatment plan. Some patients need this test once during treatment, while others may need it more often if they have kidney issues or take other medications that affect levofloxacin levels.
  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