-1651085832.png){kind=logo}
Home
HelpTest Code CARFT Carbamazepine, Free and Total, Serum
Additional Codes
CNE Order Code: Carbam Free
Useful For
Monitoring carbamazepine (free and total) therapy in patients who are uremic
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 Homogeneous Microparticle Agglutination Immunoassay
CARTA: Homogeneous Microparticle Agglutination Immunoassay
Reporting Name
Carbamazepine, Free and Total, SSpecimen Type
Serum RedSpecimen Required
Container/Tube: Red top (serum gel/SST are not acceptable)
Submission Container/Tube: Plastic vial
Specimen Volume: 2 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial within 2 hours of collection.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum Red | Refrigerated (preferred) | 7 days | |
| Frozen | 28 days | ||
| Ambient | 48 hours |
Reject Due To
| Gross hemolysis | Reject |
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
Interpretation
In patients with normal kidney function, optimal response is often associated with free (unbound) carbamazepine levels greater than 1.0 mcg/mL, and toxicity may occur when the free carbamazepine is greater than or equal to 4.0 mcg/mL.
In uremic patients, the free carbamazepine level may be a more useful guide for dosage adjustments than the total level. In patients with severe uremia, subtherapeutic total carbamazepine levels in the range of 1.0 to 2.0 mcg/mL may be associated with therapeutic free levels. Toxicity may occur in these patients when the free carbamazepine level is greater than or equal to 4.0 mcg/mL (even though the total carbamazepine concentration is <15.0 mcg/mL).
As with the serum levels of other anticonvulsant drugs, total and free carbamazepine levels should be correlated with the patient's clinical condition. They are best used as a guide in dose adjustment.
Day(s) Performed
Monday through Sunday
Report Available
Same day/1 dayPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
80156
80157
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CARFT | Carbamazepine, Free and Total, S | 34545-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| CARF | Carbamazepine, Free, S | 3433-0 |
| CARTA | Carbamazepine, Tot, S | 3432-2 |
Forms
If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.