Carbamazepine, Free and Total
0090615
Ordering Recommendation
 
Mnemonic
FCARB
Methodology
Quantitative Enzyme Multiplied Immunoassay Technique
Performed
Mon, Wed, Fri
Reported
1-5 days  
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
Patient Preparation
Timing of specimen collection: Pre-dose (trough) draw - At steady state concentration.  
Collect
Plain red. Also acceptable (avoid if possible): Serum separator tube (follow preparation instructions below).  
Specimen Preparation
Separate serum from cells within 2 hours of collection. Transfer 2 mL serum to an ARUP Standard Transport Tube. (Min: 1 mL)  
Storage/Transport Temperature
Refrigerated.  
Unacceptable Conditions
Citrated plasma. Tubes that contain liquid anticoagulant.  
Remarks
Separate serum from cells ASAP.   
Stability
After separation from cells: Ambient: 5 days; Refrigerated: 5 days; Frozen: 4 months  
Reference Interval
Therapeutic Range:
 
Test Number Components Therapeutic Range:
 CARBAMAZEPINE, TOTAL Therapeutic Range: 4.0-​12.0 µg/mL
Toxic Range: Greater than 20 µg/mL
 Free CarbamazepineTherapeutic Range: 1.0-​3.0 µg/mL
Toxic Range: Greater than 3.8 µg/mL
 Percent Free Carbamazepine8.0-​35.0%
Interpretive Data
The therapeutic range is based on serum pre-dose (trough) draw at steady-state concentration. Free carbamazepine may be important to monitor in patients with altered or unpredictable protein binding capacity. Carbamazepine is also subject to drug-drug interactions due to displacement of protein binding and extensive metabolism. Cross-reactivity with metabolites may account for differences in carbamazepine among analytical methods. Calculating percent free attempts to minimize differences in assay cross-reactivity and may be useful in dose optimization.  
Note
 
CPT Code(s)
80156; 80157
Components
Component Test Code*Component Chart NameLOINC
0090616Carbamazepine, Total3432-2
0090617Carbamazepine, Free3433-0
0090618Carbamazepine, Percent Free32852-6
2010132Free Carbamazepine Dose Information 
2010133Free Carbamazepine Draw Time 
* 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
  • Atretol
  • Biston
  • Calepsin
  • Carbamazepine, Free
  • Carbatrol
  • Epimaz
  • Epitol
  • Epitrol
  • Equetro
  • Finlepsin
  • Free Carbamazepine
  • Free Tegretol
  • Protein Free Carbamazepine
  • Sirtal
  • Tegretol, Free
  • Telesmin