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Serum/plasma concentration of cefazolin (antibiotic)

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

This test measures the amount of cefazolin, a medication used to treat bacterial infections, in your blood.

Quick summary

["Knowing your cefazolin level helps doctors monitor your response to treatment and adjust dosing if needed."]

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

Key facts at a glance

LOINC
73472-3
Short code
ceFAZolin ind plt IgG SerPl Ql FC
Synonyms
ceFAZolin 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 This Test Is Done

Your healthcare provider may order this test if you’re receiving cefazolin therapy to check if the medication is working properly. It helps ensure the right amount of the drug is in your blood to fight infection without causing harmful side effects.

What to Expect Before the Test

No special preparation is usually needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re on IV cefazolin, your level may be checked through a blood sample drawn from the IV line.

What the Test Results Mean

Results show how much cefazolin is present in your blood at the time of testing. Lower levels may indicate the drug isn’t staying in your system long enough, while higher levels could suggest toxicity or improper dosing.

Possible Side Effects of Cefazolin

Cefazolin is generally safe, but rare side effects can include allergic reactions (e.g., rash, swelling) or kidney issues. If you experience severe pain, swelling, or difficulty breathing after receiving the drug, seek medical attention immediately.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Cefazolin Level

Frequently asked questions

What does my cefazolin level tell my doctor?
Your doctor uses these results to confirm the antibiotic is effective against your infection. They may adjust your treatment plan if levels are too low (requiring more frequent dosing) or too high (requiring dose reduction or switching medications).
Can I eat or drink before this test?
Typically, you can eat and drink normally unless instructed otherwise. However, if you’re on IV cefazolin, your provider may ask you to fast for a short time before the blood draw.
How long will I need to wait for my results?
Results are usually available within 1–3 business days, depending on your lab. Your doctor will discuss them with you during your follow-up visit.
  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