Carbamazepine, Free, Serum
Use
Monitoring of unbound or free carbamazepine levels in patients where total carbamazepine result is within the therapeutic range but the patient is experiencing side effects. It is also useful for monitoring carbamazepine (free) therapy in patients who are uremic. The free drug is the active form and can cross into the brain's interstitial space where it exerts its pharmacological effect. Measurement of free carbamazepine levels is critical in patients with altered protein binding due to conditions like hypoalbuminemia, kidney disease, and the concurrent administration of drugs affecting protein binding.
Special Instructions
When not ordering electronically, a Therapeutics Test Request form (T831) should be completed, printed, and submitted alongside the specimen. Proper specimen handling includes centrifugation and aliquoting serum into a plastic vial within 2 hours of collection.
Limitations
Analysis requires fresh serum with normal protein content. Specimens exposed to significant heat or conditions causing protein denaturation may result in artificially elevated free carbamazepine levels. Hemolyzed, lipemic, or icteric specimens beyond analytical interference thresholds will result in test cancellation.
New York Approved
Methodology
Immunoassay (Homogeneous Microparticle Agglutination Immunoassay)
Biomarkers
LOINC Codes
- 3433-0
- 3433-0
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
2 mL
Minimum Volume
1 mL
Container
Red top (serum gel/SST are not acceptable); Submission: Plastic vial
Collection Instructions
Centrifuge and aliquot serum into a plastic vial within 2 hours of collection.
Causes for Rejection
Gross hemolysis
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 48 hours |
| Refrigerated | 7 days |
| Frozen | 28 days |