Skip to content

Carbamazepine Serum Concentration (Mass Concentration)

Published: August 9, 2026Updated: August 14, 2026

This test measures the amount of carbamazepine, a medication used to treat certain types of seizures or nerve pain, in your blood.

Quick summary

["Your doctor may check this level to ensure you’re taking the right dose and to avoid side effects."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 14, 2026Editorial policy

Key facts at a glance

LOINC
29148-4
Short code
CARB-B
Synonyms
carBAMazepine Bnd SerPl-mCnc
Category
chemistry
Sample
serum
Container
Red-top serum collection tube or serum separator tube (SST); avoid gel barrier tubes if performing certain immunoassays—consult lab-specific requirements.
Units
N/A
Ref low
2.8
Ref high
9.6
Critical range
2 N/A – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Immunoassay (e.g., enzyme immunoassay, fluorescence polarization immunoassay, or chemiluminescent immunoassay)
CPT
80157
SNOMED
101314000
Specimen volume
1.0 mL serum (minimum 0.5 mL)
Stability
Serum is stable at room temperature for up to 6 hours, refrigerated (2-8°C) for up to 7 days, and frozen at -20°C for up to 30 days. Avoid repeated freeze-thaw cycles.
Hemolysis max
100
Lipemia max
300
Icterus max
50
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your healthcare provider may order this test if you’re taking carbamazepine to manage epilepsy, neuropathic pain, or bipolar disorder. It helps monitor your medication levels to prevent toxicity or insufficient effectiveness.

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 blood. It usually takes a few minutes, and you may feel a brief pinch or discomfort.

What the Results Mean

Results help your doctor determine if your carbamazepine levels are within the safe range for your condition. Too little may mean your medication isn’t working, while too much could lead to side effects like dizziness, drowsiness, or nausea.

Common Side Effects to Watch For

If your levels are too high, you might experience dizziness, blurred vision, confusion, or stomach upset. If you notice these symptoms, contact your doctor immediately.

Reference range

Therapeutic reference range for total carbamazepine is typically 4.0-12.0 µg/mL; bound carbamazepine is the protein-bound fraction (approximately 70-80% of total in patients with normal albumin and without significant renal/hepatic dysfunction). Bound fraction reference range is approximately 2.8-9.6 µg/mL.N/A

Specimen: serum

No fasting required. Sample should ideally be drawn as a trough level, just before the next scheduled dose, to reflect steady-state minimum concentration and assess therapeutic adequacy.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Carbamazepine levels are critical for balancing treatment efficacy and safety, especially in patients with epilepsy or nerve pain. Abnormal levels can affect how well the drug controls seizures or pain, or may cause serious side effects like rash, liver issues, or bone marrow problems. Regular monitoring helps adjust doses to keep you stable.

Short name

Carbamazepine Level

Frequently asked questions

Why might my doctor want to check my carbamazepine level more often?
Your doctor may order more frequent checks if you’ve recently started taking carbamazepine, if you’ve missed doses, if you’re experiencing side effects, or if you’re having changes in your condition (like new seizures or pain). Certain medications or health conditions can also affect how carbamazepine works in your body.
What happens if my carbamazepine level is too low?
If your level is too low, your seizures or pain may not be controlled effectively. Your doctor may increase your dose or adjust your medication schedule to bring your levels back into the safe range.
Can I eat or drink anything before this test?
You can eat and drink normally before this test, unless your doctor has given you specific instructions. Blood tests don’t require fasting unless they’re for other substances that do.
  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 14, 2026. · Read our editorial policy