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Serum or Plasma Concentration of Cefazolin (Antibiotic Monitoring)

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

This test measures the amount of the antibiotic cefazolin in your blood or plasma/serum to check if it’s working properly and to avoid potential side effects.

Quick summary

["This test helps doctors monitor your response to cefazolin therapy and ensure safe dosing."]

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

Key facts at a glance

LOINC
73473-1
Short code
ceFAZolin ind plt IgM SerPl Ql FC
Synonyms
ceFAZolin ind plt IgM 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 healthcare provider may order this test if you’re receiving cefazolin treatment, such as for infections like skin, bone, or joint infections. It helps track how much of the drug is in your blood and whether it’s reaching the right levels to fight infection without causing harm.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or vein for a blood draw. If you’re on a continuous IV infusion of cefazolin, your level may be checked during or after treatment.

What the Test Results Mean

Results show the concentration of cefazolin in your blood. Lower-than-expected levels may mean the drug isn’t working well, while very high levels could indicate side effects or improper dosing. Your doctor will interpret these results in the context of your treatment plan.

Possible Side Effects and Risks

Cefazolin is generally safe, but high levels in the blood can sometimes cause allergic reactions, kidney issues, or nerve problems. If you experience rash, swelling, or trouble breathing after starting this drug, contact your doctor immediately.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cefazolin Level

Frequently asked questions

What does this test tell your doctor?
This test helps assess whether your cefazolin dose is therapeutic (effective against infection) and safe. It also guides adjustments to avoid toxicity or insufficient antibiotic levels, especially in patients with kidney problems or those receiving other medications that interact with antibiotics.
How often should this test be done?
The frequency depends on your treatment plan. For example, if you’re receiving cefazolin intravenously, your doctor may order this test every few days to monitor levels closely. Oral cefazolin may require less frequent checks, often just at the start or during dose adjustments.
What if I miss a dose or have side effects?
If you miss a dose, contact your doctor to reschedule. If you experience side effects like nausea, diarrhea, or allergic reactions, seek medical attention right away. Never adjust your dose yourself—always follow your healthcare provider’s instructions.
  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