Normal Reference Ranges
Adult
4.0 - 12.0 mcg/mL
Pediatric
4.0 - 12.0 mcg/mL
Clinical Significance
Monitors anticonvulsant therapy. Toxicity causes ataxia, nystagmus, diplopia, hyponatremia (SIADH), and cardiac conduction delays.
Causes of High
- Carbamazepine toxicity
- Inhibition of CYP3A4 metabolism
Causes of Low
- Subtherapeutic dose
- Auto-induction of metabolism (typically occurs in first 2-4 weeks)