Collect: Plain red. Also acceptable: Lavender (EDTA), pink (K2EDTA), or green (sodium or lithium heparin).
Specimen Preparation: Separate serum or plasma from cells ASAP or within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.3 mL)
Storage/Transport Temperature: Refrigerated.
Unacceptable Conditions: Serum or plasma separator tubes. Grossly hemolyzed specimens.
Stability (collection to initiation of testing): After separation from cells: Ambient: 6 weeks; Refrigerated: 6 weeks; Frozen: 6 weeks
Reference Interval:
Therapeutic range not well established.
Interpretive Data:
The proposed therapeutic range for seizure control is 5-20 µg/mL. Pharmacokinetics varies widely, particularly with co-medications, age, and/or compromised renal function.
