ARUP's Laboratory Test Directory

0090615: Carbamazepine, Free & Total

Test Mnemonic: FCARB
Methodology: Immunoassay

Performed: Mon-Fri

Reported: 1-4 days

Specimen Required:  
Collect: One 7 mL plain red.  (Min: 3 mL)

Transport: 2 mL serum at 2-8°C.  (Min: 1 mL) Submit specimen in an ARUP Standard Transport Tube.

Pediatric Collection/Transport: 1 mL serum at 2-8°C.

Remarks: Separate serum from cells ASAP. 

Unacceptable Conditions: EDTA plasma. Separator tubes.

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:
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 Carbamazepine, total; 80157 Carbamazepine, free

 

 

 
All ARUP Sites:        www.aruplab.com     ·     www.arupconsult.com     ·     www.arup.utah.edu     ·     www.childx.org     ·     www.utahblood.org