Ceftriaxone (Antibiotic Concentration in Serum/Plasma)
This test measures the amount of ceftriaxone, a broad-spectrum antibiotic, in your blood. It helps doctors monitor your response to treatment and ensure appropriate dosing.
["This test helps track antibiotic levels to guide treatment effectiveness and avoid potential side effects."]
Key facts at a glance
- LOINC
- 73041-6
- Short code
- CRO-NAB
- Synonyms
- cefTRIAXone (neut) IgM SerPl Ql FC
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top clot tube for serum; EDTA or sodium heparin tube for plasma
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- flow-cytometry
- CPT
- 82784
- Specimen volume
- 5 mL whole blood (minimum 2 mL)
- Stability
- Serum/plasma stable for 24 hours at room temperature (20-25°C), 7 days at 2-8°C. For longer storage, freeze at -20°C or below; avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 48–168 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order this test if you’re receiving intravenous ceftriaxone therapy, particularly for infections like pneumonia, sepsis, or certain bacterial infections. It helps ensure the antibiotic is working at the right concentration in your bloodstream.
What to Expect Before the Test
No special preparation is needed. You may have a small needle inserted into your vein (venipuncture) or a blood sample drawn from your arm. If you’re receiving IV antibiotics, your blood may be drawn from the same site.
What the Test Results Mean
Results help your doctor determine if your antibiotic levels are therapeutic (effective) or too low/high. They may adjust your treatment plan based on these findings.
Common Reasons for Testing
Doctors may check ceftriaxone levels if you’re taking the medication long-term, if you have kidney or liver issues, or if you’re experiencing side effects like kidney damage or allergic reactions.
Reference range
Negative: No cefTRIAXone-dependent neutrophil-reactive IgM antibodies detected. Positive: Presence of cefTRIAXone-dependent neutrophil-reactive IgM antibodies detected, suggesting drug-induced immune-mediated neutropeniaN/A
No special patient preparation required. Specimen should be collected prior to administration of subsequent cefTRIAXone doses when possible. Document the timing of last drug exposure and any transfusion history on the requisition.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: Monitoring Antibiotic Levels
Short name
Ceftriaxone Level
Frequently asked questions
Why might my doctor want to check my ceftriaxone levels?
How often will I need this test?
What happens if my test results are abnormal?
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 16, 2026. · Read our editorial policy