81992:CARBAMAZEPINE, FREE and TOTAL
Author PeaceHealth Laboratories
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| Alias Names: |
Tegretol |
| Methodology: |
Immunoassay |
| Edit Date: |
11/16/2010 |
| Components: |
Carbamazepine, Total / Carbamazepine, Free (Carbamazepine Free is not available without a Carbamazepine Total.) |
| Performed: |
Monday-Friday |
| Released: |
1-4 days after setup at PeaceHealth Laboratories’ reference lab. |
| CPT Code: |
80156-90 / 80157-90 |
| Specimen Collection Details |
| Collection: |
One 5 mL red top tube. Do not use serum separator tube (SST). |
| Handling: |
Allow to clot, centrifuge and immediately separate serum from cells into a plastic vial. Refrigerate. |
| Stability: |
5 days ambient, 5 days refrigerated, or 4 months frozen. |
| Standard Volume: |
2 mL serum |
| Minimum Volume: |
1 mL serum |
| Transport: |
Refrigerated. |
| Comments: |
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.
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| Rejection Criteria: |
Use of SST or PST; EDTA or heparin plasma. |
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Carbamazepine, Total |
Therapeutic Range: 4.0-12.0 µg/mL |
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Toxic Range: > 20 µg/mL
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Carbamazepine, Free |
Therapeutic Range: 1.0-3.0 µg/mL
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Toxic Range: > 3.8 µg/mL |
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Percent Free Carbamazepine |
8.0-35.0% |
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