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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Carbamazepine

Test Code(s): MAZE / TEG

CPT Code(s): 80156

Methodology: Particle Enhanced Turbidometric Inhibition Immunoassay (PETINIA)

Clinical Significance: Anticonvulsant.

Request Form: UWHC Laboratory Request Form (UWH 1289220, 4004202); Write in test if not on form.

Days Performed: Daily, 24 hours.

Turnaround Time: Stat: 1 hour.
Routine: 4 hours.


Specimen Requirements

Specimen: Blood

Collection Instructions: Collect specimen 15 - 30 minutes prior to morning dose.

Collection Container: Preferred: Red top

Collection Volume: Preferred: 2 mL
Pediatrics: 0.4 mL

Sample Analyzed: Serum

Volume Required: Preferred: 1 mL
Pediatrics: 0.2 mL

Specimen Processing: Centrifuge within two hours of collection. Transfer cell-free serum to plastic vial. Refrigerate.

Specimen Transport: Transport specimen to UWHC Core Laboratory (B4/220). Transport with coolant pack if coming from outreach location.

Unacceptable Criteria: Specimens collected in red cap with yellow ring (SST) tubes are not acceptable.


Interpretation

Generally effective therapeutic concentration: 4-12 mcg/mL 

 

Toxic: > 15 mcg/mL

Critical Calls: View

Additional Information: Result of "BELOW" indicates that the result is below the method detection limit of 0.5 mcg/mL. The half-life is approximately 12-36 hours. The peak level occurs in 2-6 hours. Carbamazepine is extensively hepatically metabolized. The principle metabolite, carbamazepine-10,11-epoxide, is an active metabolite whose plasma concentration may be increased in the presence of enzyme inducers or valproic acid. Carbamazepine undergoes autoinduction of metabolism (maximal effect seen in three to four weeks) which decreases the half-life and plasma concentration over time. Drug interactions do occur and blood levels and half-life tend to be decreased in the presence of other anticonvulsant drugs because of enzyme induction.
Tegretol

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