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Levofloxacin in Serum/Plasma (Mass Concentration)

Published: August 9, 2026Updated: August 17, 2026

This test measures the amount of the antibiotic levofloxacin in your blood, either serum or plasma, to check if it’s working as intended in your treatment.

Quick summary

["This helps doctors confirm whether your antibiotic dose is appropriate for your infection."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
21368-6
Short code
levoFLOXacin SerPl-mCnc
Synonyms
levoFLOXacin SerPl-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
17
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 levofloxacin for a bacterial infection, such as pneumonia, urinary tract infection, or skin infections. It helps ensure the drug is at the right level to fight the infection without causing unnecessary side effects.

What Does This Test Measure?

Levofloxacin is a fluoroquinolone antibiotic used to treat certain bacterial infections. This test quantifies how much of the drug is present in your bloodstream, measured in micrograms per milliliter (mcg/mL).

How Is the Sample Collected?

A blood sample is drawn from a vein, usually in your arm, by a healthcare professional. The blood is then separated into serum or plasma for testing.

What Are Possible Results?

Results are typically reported as a specific concentration value (e.g., 0.5 mcg/mL to 5 mcg/mL), but your exact range depends on your treatment plan and medical needs. Your doctor will interpret these results in relation to your condition and prescribed dose.

Reference range

NCBI: NSE 0-17 ng/mLN/A

Specimen: serum

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Levofloxacin Level

Frequently asked questions

What Does a High or Low Level Mean?
A high level may indicate the drug is too concentrated, potentially causing side effects like nausea, dizziness, or tendon pain. A low level might mean the infection isn’t fully treated, so your doctor may adjust your dose.
What Does This Test Tell Me About My Infection?
This test helps confirm whether levofloxacin is effectively targeting the bacteria causing your infection. It doesn’t diagnose the infection itself but ensures the drug is working properly.
How Often Will I Need This Test?
Your doctor may schedule this test during or after your treatment course, depending on your infection type and response. Follow their instructions for timing and frequency.
  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 17, 2026. · Read our editorial policy