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Carbamazepine, Serum or Plasma Mass Concentration

Published: August 9, 2026Updated: August 17, 2026

This test measures the amount of carbamazepine, a medication used to control certain types of seizures, in your blood.

Quick summary

["Knowing your carbamazepine levels helps your doctor adjust your dose for better seizure control and fewer side effects."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
103604-5
Short code
CBZEPU
Synonyms
Carbamazepine EP Ur-mCnc
Category
chemistry
Sample
urine
Container
Sterile, leak-proof urine container; preferably a screw-capped, preservative-free plastic container without additives
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
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
CPT
80346
SNOMED
395117009
Specimen volume
10-50 mL of random or 24-hour urine collection
Stability
Ambient: 8 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
48–96 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you’re taking carbamazepine to manage epilepsy or nerve pain. It helps ensure your medication is working at the right level in your bloodstream.

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.

What the Results Mean

Results help your doctor check if your carbamazepine dose is safe and effective. Too little may not control your seizures, while too much could cause serious side effects.

Possible Side Effects or Risks

Blood tests are generally safe, but rare risks include bruising, fainting, or infection at the needle site. Your doctor will guide you on any precautions.

Reference range

Therapeutic: 4-12 mcg/mLN/A

Specimen: urine

No special preparation required. Patient should be on a stable carbamazepine dose for at least 5-7 days prior to testing for accurate interpretation. Note time of last dose on requisition.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Carbamazepine Level

Frequently asked questions

Why do doctors check carbamazepine levels regularly?
Doctors check levels to ensure the medication stays within a safe range for your condition. This helps avoid side effects while maintaining seizure control.
What happens if my carbamazepine level is too high?
If levels are too high, your doctor may adjust your dose or monitor you closely for symptoms like nausea, confusion, or slow breathing. Immediate medical attention may be needed in severe cases.
Can diet or other medications affect carbamazepine levels?
Yes, certain foods, vitamins, or other drugs (like St. John’s wort) can change how carbamazepine works in your body. Always tell your doctor about all medications and supplements you take.
  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 17, 2026. · Read our editorial policy