Carbamazepine, Free and Total (INACTIVE as of 02/17/15: Refer to 2011763)
Ordering Recommendation
Quantitative Enzyme Multiplied Immunoassay Technique
Mon, Wed, Fri
1-5 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Timing of specimen collection: Pre-dose (trough) draw - At steady state concentration. 
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
Unacceptable Conditions
Citrated plasma. Tubes that contain liquid anticoagulant. 
Separate serum from cells ASAP.  
After separation from cells: Ambient: 5 days; Refrigerated: 5 days; Frozen: 4 months 
Reference Interval
Therapeutic Range:
Test Number
Therapeutic Range:
 Carbamazepine, TotalTherapeutic Range: 4.0-12.0 µg/mL
Toxic Range: Greater than 20 µg/mL
 Carbamazepine, FreeTherapeutic Range: 1.0-3.0 µg/mL
Toxic Range: Greater than 3.8 µg/mL
 Carbamazepine, Percent Free8.0-35.0%

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.

CPT Code(s)
80156; 80157
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.
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