Ordering Recommendation

Optimize drug therapy and monitor patient adherence.

Mnemonic
CARB EPOXT
Methodology

Quantitative Liquid Chromatography-Tandem Mass Spectrometry

Performed

Mon

Reported

1-8 days

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation

Timing of specimen collection: Pre-dose (trough) draw - At steady state concentration.

Collect

Plain red. Also acceptable: Lavender (K2 or K3EDTA) or pink (K2EDTA).

Specimen Preparation

Separate serum or plasma from cells within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.5 mL)

Storage/Transport Temperature

Frozen

Unacceptable Conditions

Whole blood. Gel separator tubes, light blue (citrate), or yellow (SPS or ACD solution).

Remarks
Stability

After separation from cells: Ambient: 48 hours; Refrigerated: 1 week; Frozen: 1 month

Reference Interval

Effective November 13, 2017

Available Separately
Components
Therapeutic Range
No Carbamazepine-10, 11 Epoxide Not well established
Toxic:  Greater than 15.0 µg/mL
No Total Carbamazepine Therapeutic Range: 4.0-12.0 µg/mL
Toxic:  Greater than 15.0 µg/mL

Interpretive Data

The therapeutic range is based on serum pre-dose (trough) draw at steady-state concentration. The carbamazepine metabolite, Carbamazepine-10, 11-Epoxide, has anticonvulsant activity and a proposed therapeutic range of 0.4-4 µL/mL. 

A rare, adverse drug reaction to carbamazepine therapy includes Stevens-Johnson syndrome or toxic epidermal necrolysis. Patients of Asian ancestry with the presence of the HLA-B*15:02 have an increased risk for this carbamazepine-induced, life-threatening reaction. Pharmacogenetic testing for HLA-B*15:02 is recommended prior to treatment for patients at risk of carbamazepine hypersensitivity. This information has been included in the FDA-approved label for carbamazepine (<https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&varApplNo=016608>) and in the guideline from the Clinical Pharmacogenetics Implementation Consortium (https://www.pharmgkb.org/guidelines). (HLA-B*15:02 Genotyping, Carbamazepine Hypersensitivity, ARUP test code 2012049.)

A combination of therapeutic drug monitoring with HLA-B*15:02 pharmacogenetics genotyping may benefit patients at increased risk of developing carbamazepine-induced adverse events due to rare genotypes other than the HLA-B*15:02 variant allele.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Compliance Category

Laboratory Developed Test (LDT)

Note
Hotline History
N/A
CPT Codes

80156; 80161

Components
Component Test Code* Component Chart Name LOINC
0090616 Carbamazepine, Total 3432-2
0098427 Carbamazepine 10-11 Epoxide 9415-1
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • 11 Epoxide
  • Atretol
  • Biston
  • Calepsin
  • Carbamazepine - 10,11 Epoxide, Serum or Plasma
  • Carbamazepine and Epoxide Metabolite
  • Carbamazepine Metabolite
  • Carbamazepine-10
  • Carbatrol
  • Epimaz
  • Epitol
  • Epitrol
  • Epoxide 10, 11
  • Equetro
  • Finlepsin
  • Sirtal
  • Tegretol, Metabolite
  • Telesmin
Carbamazepine Epoxide and Total