Carbamazepine

Test Code

CARBA

Alias/See Also

Epic: LAB21

Carbatrol (Carbamazepine)
Carbamazepine (Carbatrol, Tegretol)
Tegretol (Carbamazepine)

Preferred Specimen

Specimen Type: Serum
Collection Container: Serum gel
Specimen Volume: 3 mL

Minimum Volume

0.3 mL

Instructions

In a patient on regular medication regimen, the sample should be drawn immediately prior to next carbamazepine dose.
Centrifuge and separate cells after clot formation and within 4 hours of collection.

Transport Container

Plastic vial

Specimen Stability

Room temperature: 24 hours
Refrigerated: 7 days
Frozen: 14 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Unlabeled, mislabeled, wrong tube type, hemolyzed, QNS, exceeds specimen stability requirements.

Methodology

Chemiluminescent microparticle immunoassay (CMIA)

Setup Schedule

Daily

Report Available

Same day

Limitations

For diagnostic purposes, results should be used in conjunction with other data: symptoms, results of other tests, clinical impressions, etc.
Potentially interfering substances include : Hemoglobin >500 mg/dL; Bilirubin >20 mg/dL; Triglycerides >3000 mg/dL; Total Protein >12 g/dL
Patients receiving mouse monoclonal antibodies for diagnosis or treatment may develop Human anti-mouse antibodies (HAMA). HAMA may cause falsely elevated or decreased values when tested with assay kits which employ mouse monoclonal antibodies. Additional information may be required for diagnosis.
Heterophilic antibodies in human serum can react with reagent immunoglobulins, interfering with in vitro immunoassays.

Reference Range

4.00 - 12.00 µg/mL

Clinical Significance

Carbamazepine (Tegretol) is used in the control of partial seizures with both temporal lobe and psychomotor symptoms, and for generalized tonic-clonic seizures. It is also used for analgesia in trigeminal neuralgia.

Carbamazepine exhibits a volume of distribution of 1.4 L/kg with an elimination half-life of 15 hours. Protein binding averages 70%.

Carbamazepine-10,11-epoxide (CBZ10-11) is an active metabolite that represents the predominant form of the drug in children. The volume of distribution of CBZ10-11 is 1.1 L/kg, and the half-life is 5-8 hours.

Aplastic anemia and agranulocytosis are rare side effects of treatment with carbamazepine; baseline hematologic data should be documented before treatment is initiated.

Toxicity associated with carbamazepine overdose occurs when the blood level is 15.0 mcg/mL or higher and is typified by irregular breathing, muscle irritability, and hyperreflexia; followed by hyporeflexia, tachycardia, hypotension, and impaired consciousness with coma in severe toxicity. The higher the blood level, the more severe the symptoms.

Performing Laboratory
Inova Laboratories
2832 Juniper Street
Fairfax, VA 22031

Last Updated: March 6, 2023
Last Review: N. Wolford, March 6, 2023

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.