Test Directory

Clear All
Test Code
FRCB
Test Name
Carbamazepine, Free
CPT Codes
80157
Expected Turnaround Time
Same day
Clinical Utility

The carbamazepine that circulates in blood is 75% protein bound under normal circumstances. Since neurologic activity and toxicity of carbamazepine are directly related to the unbound fraction of the drug, measurement of the free or unbound drug may be necessary where altered protein binding is possible, such as in hypoalbuminemia, pregnancy, renal or hepatic failure, old age, or use of concomitant drug therapy.
Specimen and Container Info

Specimen

Container

Volume

Serum

Red Top, Plain 

3 mL

Plasma

Dark Green Top (Lithium Heparin) 

3 mL
Collection Instructions

Specimens collected in separator tubes will be rejected.  
Processing and Submission Instructions
  1. Centrifuge specimens for 5 minutes at 3000 rpm.
  2. Transfer serum or plasma to a plastic aliquot tube.
Transport Instructions

Transport to the laboratory refrigerated. 
Stability Requirements

Refrigerated

 1 month

Frozen

3 months
Causes for Rejection
  • Specimens collected in separator tubes will be rejected.  
  • Serum/Plasma volumes less than 1 mL will be rejected.
Methodology
Enzyme Immunoassay (EIA)
Reference Intervals

Age

Reference Interval

Units

All Ages

0.5 - 3.0

µg/mL 
Critical Values

Age

Critical Value

Units

All Ages

>=4.1

µg/mL 
Performing Location
Roble Road Core Laboratory
Alternate Names
  • Epitol
  • Equetro
  • Tegretol
Testing Schedule
Routine daily, STAT testing available
The American Medical Association (AMA) Current Procedural Terminology (CPT) codes published by HNL Lab Medicine are guidelines and are intended for informational purposes only. CPT coding is the exclusive responsibility of the billing entity. View the Terms.
© 2026 HNL Lab Medicine. All rights reserved.