Sign in →

Test Code PTN Phenytoin (Dilantin), Total, Plasma


Used for therapeutic drug monitoring. Phenytoin is the most widely used anticonvulsant. It is effective against grand mal and the generalized spread of seizures with focal origin.

Performing Laboratory

St. Mary's Regional Medical Center-Chemistry

Specimen Requirements

Container/Tube: Light green-top (lithium heparin) tube

Specimen: 1 mL of lithium heparin plasma
Transport Temperature: Ambient
Collection Instructions: Draw specimen just prior to administration of next dose for therapeutic response.
Note: 1. Indicate plasma.
           2. Label specimen appropriately (plasma).


Reference Values

Therapeutic concentration: 10-20 mcg/mL

Potentially toxic concentration: >30 mcg/mL

Call criteria (automatic call-back): >25 mcg/mL

Day(s) Test Set Up

Monday through Sunday

Available STAT