Test Name: Carbamazepine
Health Link Test Code: TEG
LIS Test Code: MAZE
CPT Code(s): 80156
Methodology: Enzyme Immunoassay
Days Performed: Daily, 24 hours.
In-Lab Turnaround Time: 4 hours.
Stat In-Lab Turnaround Time: 1 hour.
Collection Container: Red top
Collect specimen 15 - 30 minutes prior to morning dose.
Collection Volume: 2 mL
Pediatric Collection Volume: 0.4 mL
Sample Analyzed: Serum
Testing Volume: 1 mL
Pediatric Testing Volume: 0.2 mL
Centrifuge within two hours of collection. Transfer cell-free serum to plastic vial. Refrigerate.
Transport specimen to UWHC Hospital Laboratory. Transport with coolant pack if coming from clinic location.
Specimens collected in red cap with yellow ring (SST) tubes are not acceptable.
Generally effective therapeutic concentration: 4.0-12.0 ug/mL
Critical: 15.0 ug/mL
Interpretation Type: Interpretive Guidelines
Critical Calls: yes
Result of "BELOW" indicates that the result is below the method detection limit of 1.9 ug/mL. The half-life is approximately 12-36 hours. The peak level occurs in 2-6 hours. Carbamazepine is extensively hepatically metabolized. The principle metabolite, carbamazepine-10,11-epoxide, is an active metabolite whose plasma concentration may be increased in the presence of enzyme inducers or valproic acid. Carbamazepine undergoes autoinduction of metabolism (maximal effect seen in three to four weeks) which decreases the half-life and plasma concentration over time. Drug interactions do occur and blood levels and half-life tend to be decreased in the presence of other anticonvulsant drugs because of enzyme induction.