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HelpTest ID CARFT Carbamazepine, Free and Total, Serum
Useful For
Monitoring carbamazepine (free and total) therapy in uremic patients
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| CARTA | Carbamazepine, Tot, S | Yes | Yes |
| CARF | Carbamazepine, Free, S | Yes | Yes |
Method Name
CARF: Ultrafiltration Followed by Immunoassay
CARTA: Immunoassay
Reporting Name
Carbamazepine, Free and Total, SSpecimen Type
Serum RedContainer/Tube: Red top
Specimen Volume: 2 mL
Collection Instructions: Red-top tubes should be centrifuged and aliquoted within 2 hours of collection.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum Red | Refrigerated (preferred) | 14 days |
| Frozen | 28 days | |
| Ambient | 14 days |
Clinical Information
Carbamazepine (Tegretol) is an effective treatment for complex partial seizures, with or without generalization to tonic-clonic seizures. It is frequently administered in conjunction with other antiepileptic agents, such as phenytoin and valproic acid.
Under normal circumstances, the carbamazepine that circulates in blood is 75% protein bound. In severe uremia, carbamazepine may be displaced from protein, resulting in a higher free (unbound) fraction of the drug circulating in blood. Since neurologic activity and toxicity are directly related to the circulating free fraction of drug, adjustment of dosage based on knowledge of the free carbamazepine level may be useful in patients with severe uremia.
Reference Values
CARBAMAZEPINE, TOTAL
Therapeutic: 4.0-12.0 mcg/mL
Critical value: ≥15.0 mcg/mL
CARBAMAZEPINE, FREE
Therapeutic: 1.0-3.0 mcg/mL
Critical value: ≥4.0 mcg/mL
Cautions
Fresh serum with normal protein content is required for optimal analysis.
Specimens subjected to significant heat or other factors that cause protein denaturation demonstrate an artifactually increased free carbamazepine.
Day(s) Performed
Monday through Sunday; Continuously
Report Available
Same day/1 dayPerforming Laboratory
Mayo Medical Laboratories in Rochester
Test Classification
This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer’s instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
80156-Carbamazepine, Total, S
80157-Carbamazepine, Free, S