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Carbamazepine concentration in serum

Published: August 9, 2026Updated: August 10, 2026

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

Quick summary

["This helps doctors monitor your dose for safety and effectiveness."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 10, 2026Editorial policy

Key facts at a glance

LOINC
60291-2
Short code
CARB
Synonyms
carBAMazepine Spec Ql
Category
chemistry
Sample
serum
Container
Red-top serum tube (no anticoagulant) or serum separator tube (SST/gold-top). Avoid gel separator tubes if LC-MS/MS confirmation is anticipated.
Units
N/A
Ref low
4
Ref high
12
Critical range
— – 20 N/A
Fasting
false
Population
adult
Sex
all
Age range
0–120 years
Method
Immunoassay (e.g., Chemiluminescent Microparticle Immunoassay, Enzyme Multiplied Immunoassay Technique, or Fluorescence Polarization Immunoassay); confirmation by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) if needed
CPT
80156
SNOMED
102691009
Specimen volume
1.0-2.0 mL serum (minimum 0.5 mL); collect 3-5 mL whole blood in standard serum tube
Stability
Serum stable at room temperature (20-25°C) for 24 hours; refrigerated (2-8°C) for 7 days; frozen (-20°C or below) for 30 days. Avoid repeated freeze-thaw cycles. Separate serum from cells within 2 hours of collection.
Hemolysis max
100
Lipemia max
500
Icterus max
25
TAT
4–24 hours
Order
routine

Why Is This Test 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 low blood counts, and ensures the drug stays at safe levels in your body.

What to Expect During the Test

A small blood sample is taken from a vein, usually in your arm. You may feel a slight pinch, but it only takes a few minutes. No special preparation is needed, though you should avoid eating or drinking for a short time before the test if instructed.

Possible Results and Next Steps

Results are compared to a general range of what’s considered typical for this medication. If levels are too high, your dose may need adjustment to avoid risks. If too low, your provider may increase it to improve effectiveness.

Common Side Effects or Considerations

Carbamazepine can cause side effects like drowsiness, nausea, or skin rash. If you experience severe symptoms (e.g., allergic reactions, unusual bleeding), contact your doctor immediately.

Reference range

Therapeutic range: 4.0-12.0 mcg/mL (mcg/mL = ug/mL). Trough levels should be drawn just before the next dose. Optimal therapeutic range may vary by indication and individual patient factors.N/A

Specimen: serum

No fasting required. Draw specimen as a trough level (immediately before next scheduled dose) for accurate therapeutic drug monitoring. Patient should be at steady-state dosing (typically after 2-5 days of consistent dosing) for meaningful interpretation. Document time of last dose and time of specimen collection.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Carbamazepine Level

Frequently asked questions

Why might my carbamazepine levels be checked more often?
If you’re new to carbamazepine, have liver or kidney issues, or take other medications that interact with it (like certain antibiotics or birth control), your provider may check levels more frequently to avoid unsafe levels.
What if my test results are outside the usual range?
Your doctor will discuss the results with you and may adjust your dose, suggest lifestyle changes (like avoiding grapefruit juice), or check for other health factors affecting your metabolism.
Can I eat or drink before this test?
Follow your healthcare provider’s instructions—some tests require fasting, while others don’t. Generally, avoid food/drink for 8–12 hours before the draw unless specified otherwise.
  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 10, 2026. · Read our editorial policy