Skip to content

Carbamazepine (Serum/Plasma Eptopic Concentration)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of carbamazepine, a medication used to treat certain types of seizures and nerve pain, in your blood at a specific time (the trough level). It helps doctors monitor your dose to ensure it’s effective and safe.

Quick summary

["This test helps adjust your medication to avoid side effects or reduce seizures."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
78443-9
Short code
Deprecated carBAMazepine EP Trough SerPl
Synonyms
Deprecated carBAMazepine EP Trough SerPl
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0.8
Ref high
1.2
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85610
SNOMED
396252006
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you’re taking carbamazepine to manage epilepsy or another condition. The trough level is taken just before the next dose to check if the medication is at a safe and effective concentration in your blood.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into a vein in your arm or hand for blood collection. If you’re using a fingerstick, a small amount of blood will be taken from your fingertip.

What the Test Results Mean

Results help your doctor determine if your carbamazepine dose is working well or if adjustments are needed. They won’t provide a direct numeric range, but your doctor will interpret the result in relation to your symptoms and other health factors.

Possible Side Effects or Risks

Like all medications, carbamazepine can cause side effects, such as dizziness, drowsiness, or stomach upset. Blood tests like this help ensure your dose stays safe. Rarely, low carbamazepine levels may require a higher dose, while too much can be dangerous.

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: serum

Inform your healthcare provider if you are taking blood thinners. No special preparation required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Carbamazepine trough level

Frequently asked questions

What is the purpose of measuring carbamazepine at the trough level?
The trough level is taken to assess whether your carbamazepine concentration is within the therapeutic range—meaning it’s high enough to control seizures or pain but low enough to avoid serious side effects. This helps prevent both underdosing (which may lead to seizures) and overdosing (which can cause toxicity).
How often should I get this test?
Your doctor will decide how often you need this test based on your treatment plan, how well your medication is working, and whether you’re experiencing side effects. Follow their instructions closely.
Can I drink water before this test?
Yes, you can drink water before the test unless your doctor specifies otherwise. Avoiding food or fluids for too long may not be necessary unless instructed.
  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 16, 2026. · Read our editorial policy