Carbamazepine concentration in serum/plasma
This test measures the amount of carbamazepine, a medication used to treat certain types of seizures or nerve pain, in your blood.
["Helps monitor your carbamazepine dose for safety and effectiveness."]
Key facts at a glance
- LOINC
- 3431-4
- Short code
- CARB
- Synonyms
- carBAMazepine SerPl Ql
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube or serum separator tube (SST); plasma may be collected in green-top (lithium heparin) or lavender-top (EDTA) tube
- Units
- N/A
- Ref low
- 4
- Ref high
- 12
- Critical range
- — – 15 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay (e.g., PETINIA, EMIT, FPIA) or Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
- CPT
- 80156
- SNOMED
- 395078004
- Specimen volume
- 1.0 mL serum or plasma (minimum 0.5 mL)
- Stability
- Room temperature: 24 hours; Refrigerated (2–8°C): 7 days; Frozen (-20°C or below): 30 days; avoid repeated freeze-thaw cycles
- Hemolysis max
- 100
- Lipemia max
- 200
- Icterus max
- 25
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your healthcare provider may order this test if you’re taking carbamazepine to check if your dose is working properly. It helps prevent side effects like dizziness, drowsiness, or abnormal blood counts. Some people also get this test to adjust their medication based on blood levels.
What to Expect Before the Test
No special preparation is needed. You’ll have a small needle inserted into your arm or vein to draw a blood sample. The process is quick and usually painless. If you’re nervous, let your provider know—they can offer ways to stay comfortable.
What the Test Results Mean
Results show how much carbamazepine is in your blood at the time of testing. Your provider will compare these results to your symptoms and other health factors to decide if your dose needs to be changed.
Possible Side Effects or Considerations
Carbamazepine can affect how other medications work, so your provider may check other blood tests too. Rarely, very high or low levels can cause serious issues, so follow your provider’s instructions carefully.
Reference range
Therapeutic range: 4.0–12.0 µg/mL (mcg/mL); Toxic: >15.0 µg/mL; Optimal sampling time: immediately before next dose (trough level)N/A
No fasting required. Collect specimen as a trough level (immediately before the next scheduled dose) for accurate therapeutic drug monitoring. Patient should be on a stable dose for at least 3–5 days before sampling to reach steady-state concentration.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Carbamazepine Level
Frequently asked questions
Why might my provider want to check my carbamazepine level often?
What if my test results are outside the usual range?
Does this test hurt?
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 14, 2026. · Read our editorial policy