Patient Preparation Collect as a trough just prior to next dose. For patients receiving phenytoin therapy, collect as a trough at least 2 hours after IV infusion or at least 4 hours after IM injection.
Preferred Specimen(s) 1 mL serum collected in a (red-top) tube (no gel)
Transport Container Plastic screw-cap vial
Transport Temperature
- Ambient 8 hrs,
- Refrigerated 2 days
Reject Criteria Serum separator tube (SST®)
Methodology Immunoassay
Clinical Significance Phenytoin is an anticonvulsant hydantoin used for the treatment of generalized tonic-clonic (grand-mal) and complex partial seizures. Phenytoin is also used for prophylaxis in neurosurgical procedures. Phenytoin levels are monitored to assure adequate therapeutic levels are achieved and to avoid toxicity.