Serum Concentration of Cefazolin (Antibiotic)
This test measures the amount of the antibiotic cefazolin in your blood serum. It helps doctors monitor how well your body is responding to this medication, especially if you’re receiving it through an IV or injection.
["Cefazolin levels help ensure your treatment is working and avoid potential overdoses or infections from low levels."]
Key facts at a glance
- LOINC
- 73047-3
- Short code
- CEFAZ-NAB
- Synonyms
- ceFAZolin (neut) IgM SerPl Ql FC
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST, gold-top) or red-top tube for serum; EDTA plasma tube (lavender-top) or sodium heparin tube (green-top) for plasma
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- flow-cytometry
- CPT
- 86022 (Antibody identification, neutrophil, each antibody, including drug-induced antibodies)
- SNOMED
- 395112001 |Drug-induced neutropenia (disorder)|; 116859006 |Transfusion reaction (disorder)|
- Specimen volume
- 3-5 mL of whole blood (minimum 1 mL serum/plasma)
- Stability
- Serum/plasma stable for 24 hours at room temperature (20-25°C), 7 days at refrigerated temperature (2-8°C), and 30 days at frozen temperature (-20°C or lower). Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 200
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 48–168 hours
- Order
- routine
Why This Test Matters
Cefazolin is a broad-spectrum antibiotic used to treat bacterial infections. Your doctor may order this test to check if the drug is reaching the right amount in your bloodstream. This is particularly important if you’re receiving it intravenously or if you have a severe infection requiring high doses.
What to Expect Before the Test
No special preparation is needed for this test. You’ll have a small needle inserted into your arm to draw blood. The process is quick and usually painless. If you’re on a blood thinner, let your doctor know before the test.
What the Results Mean
Results show the concentration of cefazolin in your blood. Low levels may indicate the antibiotic isn’t working well, while very high levels could signal potential side effects or improper dosing. Your doctor will interpret these results in the context of your treatment plan.
Common Reasons for This Test
Doctors order cefazolin blood tests to monitor treatment effectiveness, especially in cases of serious infections like sepsis, surgical infections, or infections requiring IV antibiotics. It’s also used to adjust doses if you have kidney problems or other health conditions affecting drug metabolism.
Reference range
Negative (no detectable cefazolin-induced neutrophil IgM antibodies detected). Results reported as Positive or Negative. Positive indicates the presence of drug-dependent neutrophil-reactive IgM antibodies consistent with cefazolin-induced immune-mediated neutropenia or drug hypersensitivity.N/A
No fasting required. Specimen should be collected prior to administration of next dose if patient is currently on cefazolin therapy. Document timing of last cefazolin dose and any transfusion history on the requisition.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Cefazolin Level
Frequently asked questions
How long does it take to get my cefazolin blood test results?
Can I eat or drink before this test?
What are the possible side effects of cefazolin?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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 15, 2026. · Read our editorial policy