Carbamazepine concentration in blood (serum/plasma)
This test measures the amount of carbamazepine, a medication used to control certain types of seizures, in your blood.
["Your blood carbamazepine level helps doctors check if your dose is working safely and effectively."]
Key facts at a glance
- LOINC
- 29212-8
- Short code
- CARBFL
- Synonyms
- carBAMazepine Fld-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube (no anticoagulant) or serum separator tube (SST, tiger-top); plasma (heparin or EDTA) may be acceptable depending on assay.
- Units
- N/A
- Ref low
- 4
- Ref high
- 12
- Critical range
- — – 20 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Immunoassay (e.g., cloned enzyme donor immunoassay/CEDIA or chemiluminescent immunoassay); confirmation by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) when available
- CPT
- 80157 (Carbamazepine, total); additional confirmation by LC-MS/MS may be billed separately
- SNOMED
- 1017961004
- Specimen volume
- 1.0–2.0 mL of serum (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
- 200
- Lipemia max
- 500
- Icterus max
- 25
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Doctors may order this test if you’re taking carbamazepine to manage epilepsy or nerve pain. It helps ensure your medication levels stay within a safe range to prevent side effects like dizziness, drowsiness, or rare but serious risks like blood disorders.
What to Expect Before the Test
No special preparation is needed. You’ll have a small needle inserted into a vein in your arm, and a blood sample will be drawn. The process usually takes a few minutes.
What the Results Mean
Results are typically reported as a mass concentration (measured in micrograms per milliliter). Your doctor will compare these results to your treatment plan to adjust your dose if needed.
Possible Side Effects or Considerations
Carbamazepine can cause side effects like dizziness, nausea, or fatigue. If you experience severe symptoms such as rash, swelling, or unusual bleeding, contact your doctor immediately.
Reference range
Therapeutic range: 4.0–12.0 mcg/mL (trough level). Levels should be interpreted in the context of clinical response, dose, and timing of last dose. Refer to institutional therapeutic drug monitoring guidelines.N/A
No fasting required. Sample should be drawn as a trough level, immediately before the next scheduled dose, once steady state has been reached (typically after 2–4 days of continuous dosing or after dosage adjustment). Document date, time, and dose of last carbamazepine administration.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Carbamazepine Level
Frequently asked questions
Low carbamazepine levels may indicate insufficient medication, while high levels could signal toxicity or poor absorption. Regular monitoring helps balance effectiveness and safety.
How often should I get this test?
What if my results are outside the expected range?
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