Proceeds from website advertising help sustain Lab Tests Online. AACC is a not-for-profit organization and does not endorse non-AACC products and services.


Print this article
Share this page:
Looking for your tests results? Looking for reference ranges?
Also known as: [often referred to by brand name (see MedlinePlus Drug Information)]
Formal name: Total Carbamazepine

At a Glance

Why Get Tested?

To determine the concentration of carbamazepine in the blood to establish an appropriate dose and maintain a therapeutic level

When to Get Tested?

At regular intervals to monitor the drug's level; when indicated to detect low or excessive (potentially toxic) concentrations

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?


The Test Sample

What is being tested?

Carbamazepine is a drug that is primarily used to treat certain seizure disorders (also called epilepsy) but is also prescribed to stabilize the moods of people with bipolar disease, to ease alcohol withdrawal, and to help alleviate some types of nerve pain. It may be prescribed by itself or in combination with other antiepileptic drugs. This test measures the level of carbamazepine in the blood.

Carbamazepine levels are monitored because the drug must be maintained within a narrow therapeutic range. If the level is too low, the person may experience a recurrence of symptoms (i.e., seizures, mania, or pain); if the level is too high, the person may experience toxic side effects. Maintaining a therapeutic level of the drug can be a challenge to achieve for several different reasons:

  • Oral doses of carbamazepine are absorbed in the gastrointestinal tract at widely variable rates. 
  • Since carbamazepine is metabolized by the liver, anything that affects liver function can affect blood levels of the drug. 
  • Much of the drug is bound to plasma protein, but it is the free portion of the drug that is active. Conditions that affect protein binding of the drug may affect therapeutic effectiveness. This may occur when someone has low blood albumin, kidney failure, or when they are very young (newborn) or elderly. 
  • The metabolite of carbamazepine, carbamazepine-10 11 epoxide, is also active and contributes to the overall effect of the medication. 
  • Several drugs, if taken in conjunction with carbamazepine, may interact or affect metabolism and blood levels.

Dosages of carbamazepine must be adjusted carefully in order to reach a steady concentration in the blood. The actual amount of drug required to reach this steady state will vary from person to person and may change over time.

Carbamazepine is usually monitored long-term because it is prescribed to treat the chronic conditions epilepsy, bipolar disorder, trigeminal neuralgia, and nerve pain from diabetes.

Epilepsy affects the brain's ability to transmit electrical impulses and to regulate nerve activity. During a seizure, a person may experience changes in consciousness, alterations in sight, smell, and taste, and may experience convulsions. The frequency of seizures varies from a single episode, to occasional seizures, to recurrent seizures. Carbamazepine is prescribed to help prevent specific types of recurrent seizures.

Bipolar disorder is a mental condition that is characterized by cycles of depression and mania that may last for days, weeks, months, or years. During a depressive episode, those affected may feel sad, hopeless, worthless, and have thoughts of suicide. During a manic episode, those affected may be euphoric, irritable, use poor judgment, and participate in risky behaviors. Carbamazepine is prescribed to help even out the moods of the person with bipolar disorder, especially mania.

Trigeminal neuralgia, a condition associated with facial nerve pain and muscle spasms, and paroxysmal choreoathetosis, a movement disorder that causes involuntary movements of the limbs, trunk, and facial muscles, are also sometimes treated with carbamazepine. So is diabetic peripheral neuropathic pain, which affects the functionality, mood, and sleep patterns of approximately 10-20% of people with diabetes mellitus. (For more on this, see the Neuropathy article.)

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

People who take carbamazepine should talk to their healthcare provider about the timing of the sample collection. Often, the recommended time is when the level in the blood is at its lowest, just before the next dose is taken.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

Common Questions

Ask a Laboratory Scientist

Form temporarily unavailable

Due to a dramatic increase in the number of questions submitted to the volunteer laboratory scientists who respond to our users, we have had to limit the number of questions that can be submitted each day. Unfortunately, we have reached that limit today and are unable to accept your inquiry now. We understand that your questions are vital to your health and peace of mind, and recommend instead that you speak with your doctor or another healthcare professional. We apologize for this inconvenience.

This was not an easy step for us to take, as the volunteers on the response team are dedicated to the work they do and are often inspired by the help they can provide. We are actively seeking to expand our capability so that we can again accept and answer all user questions. We will accept and respond to the same limited number of questions tomorrow, but expect to resume the service, 24/7, as soon as possible.

Article Sources

« Return to Related Pages

NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Sources Used in Current Review

Carbamazepine (Oral Route). Mayo Clinic. Available online at through Last updated December 1, 2013. Accessed March 25, 2014.

Tegretol (Blood). University of Rochester Medical Center. Available online at through Accessed March 24, 2014.

Tegretol. Available online at through Last updated January 29, 2014. Accessed March 24, 2014.

Tammy J. Lindsay et al. Diabetic Peripheral Neuropathic Pain. American Family Physician. Available online at through Published July 2010. Accessed February 25, 2014.

Therapeutic drug levels. MedlinePlus Medical Encyclopedia. National Institutes of Health. Available online at through Last updated May 12, 2011. Accessed March 25, 2014.

Labs - DRUG Levels (Alphabetical order). Global RPh. Available online at through Last updated July 21, 2014. Accessed March 26, 2014.

Sources Used in Previous Reviews

Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry, AACC Press, Washington, DC. Pp 461.

Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. Pp 1284-1285.

Rosenbaum, J. and Covino, J. (2007 September 24). Observations on the Treatment of Bipolar Disorder. Medscape Psychiatry & Mental Health [On-line information].  Available online at through Accessed on 11/11/07.

(2007 May 1). Carbamazepine. MedlinePlus Drug Information [On-line information]. Available online at Accessed on 11/7/07.

(2003 February, Revised). Seizure Disorders. Merck Manual of Medical Information – Second Home Edition [On-line information]. Available online at through Accessed on 11/7/07.

(2007). ACPA Medications & Chronic Pain Supplement 2007. ACPA [On-line information]. PDF available for download through Accessed on 11/11/07.

Szabo, C. A. (2007 November 7). Risk of fetal death and malformation related to seizure medications. Neurology 2006;67;6-7 [On-line journal]. Available online at through Accessed on 11/11/07.

Pregnancy Issues. Epilepsy Foundation [On-line information]. Available online at through Accessed on 11/11/07.

(2007 February 14). NINDS Paroxysmal Choreoathetosis Information Page. NINDS [On-line information]. Available online through Accessed on 11/7/07.

Spearing, M. (2007 January, Updated). Bipolar Disorder. National Institute of Mental Health [On-line information]. Available online through Accessed on 11/11/07.

(© 2007). Carbamazepine, Free & Total. ARUP's Laboratory Test Directory [On-line information]. Available online at through Accessed on 11/10/07.

(© 2007). Carbamazepine (Tegretol®), Serum. LabCorp [On-line information]. Available online at through Accessed on 11/10/07.

(© 2007). Carbamazepine-10,11 Epoxide. LabCorp [On-line information]. Available online at through Accessed on 11/10/07.

(© 2007). Carbamazepine, Epoxide & Total. ARUP's Laboratory Test Directory [On-line information]. Available online at through Accessed on 11/10/07.

Carbamazepine Oral. Medscape Drug Information, Doses, Usage, and Warnings. [On-line information]. Available online through Accessed on 11/11/07.

Silberstein, S. and Wilner, A. (2007 August 13). AAN 2007: Chronic Disorders. Medscape CME [On-line information]. Available online at through Accessed on 11/11/07.

Kapoor, N. and Hamilton, R. (2007 April 27). Toxicity, Carbamazepine. emedicine [On-line information]. Available online at through Accessed on 11/11/07.

Bakerman's ABC's of Interpretive Laboratory Data, Fourth Edition, Seymour Bakerman, M.D., Ph.D., 2002. Accessed online, December 2007 at

(December 12, 2007) FDA News. Carbamazepine Prescribing Information to Include Recommendation of Genetic Test for Patients with Asian Ancestry, Connection of genetic information with medication use can improve safe use of product (online information, accessed December 2007). Available onliine at through

Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER, Bruns DE, eds. St. Louis: Elsevier Saunders; 2006, Pp.1249-1250.

Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL eds, (2005). Harrison's Principles of Internal Medicine, 16th Edition, McGraw Hill, Pg. 141.

Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER, Bruns DE, eds. St. Louis: Elsevier Saunders; 2006, Pp1249-1250, 2305.

Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry, AACC Press, Washington, DC., Pg 461, 456.

Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. McPherson R, Pincus M, eds. Philadelphia, PA: Saunders Elsevier: 2007, Pg 313.

(Sep 1, 2009) MedlinePlus Medical Encyclopedia. Drug Information, Carbamazepine. Available online at Accessed Nov 2011.

(Jan 25, 2010) U.S. Food and Drug Administration. Information on Carbamazepine (marketed as Carbatrol, Equetro, Tegretol, and generics) with FDA Alerts. Available online through Accessed 2011.