Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
1. Widely used anticonvulsan
2. Used in bipolar affective disorder, mania and depression as a mood stabilizer
3. Effective in trigeminal neuralgia
Specimen container paediatric:
Serum (SST or plain tube)
Specimen container adult:
Serum (SST or plain tube)
Minimum volume paediatric:
0.5 mL blood
Minimum volume adult:
1 mL blood
Special requirements:
Trough sample recommended as this is a better guide to therapy.
Sample stability:
Unseparated sample:
2 days
Separated sample:
5 days at 15-25°C,
7 days at 2-4°C,
4 weeks at -20°C
Interpretation :
1. CBZ induces its own metabolism
2. Metabolism is induced by phenobarbitone and phenytoin
3. Metabolism is inhibited by valproate and lamotrigine
Toxicity:
1. Dose limiting side effects include blurred vision, dizziness and ataxia
2. Erythematous rash in 5% patients
3. Syndrome of inappropriate antidiuresis may develop
Monitoring therapy:
1. Typical target range is 4 – 12 mg/L
2. The breakdown epoxide metabolite is pharmacologically active
3. Trough concentration is a better guide to therapy than dose
Reference ranges:
Therapeutic range: 4 – 12 mg/L
Other info:
Lithium heparin plasma sample also acceptable