ARUP's Laboratory Test Directory

Carbamazepine, Free and Total : 0090615

Mnemonic: FCARB

Methodology: Quantitative Enzyme Multiplied Immunoassay Technique
Performed: Mon-Fri
Reported: 1-4 days
Specimen Required: Patient Prep: 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.

Remarks: Separate serum from cells ASAP.

Unacceptable Conditions: Citrated plasma. Tubes that contain liquid anticoagulant.

Stability (collection to initiation of testing): 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; 80157
Cross References: Atretol (Carbamazepine, Free and Total), Biston (Carbamazepine, Free and Total), Calepsin (Carbamazepine, Free and Total), Carbamazepine, Free (Carbamazepine, Free and Total), Carbatrol (Carbamazepine, Free and Total), Epimaz (Carbamazepine, Free and Total), Epitol (Carbamazepine, Free and Total), Epitrol (Carbamazepine, Free and Total), Equetro (Carbamazepine, Free and Total), Finlepsin (Carbamazepine, Free and Total), Free Carbamazepine (Carbamazepine, Free and Total), Free Tegretol (Carbamazepine, Free and Total), Protein Free Carbamazepine (Carbamazepine, Free and Total), Sirtal (Carbamazepine, Free and Total), Tegretol, Free (Carbamazepine, Free and Total), Telesmin (Carbamazepine, Free and Total)