Phenytoin, Free (Dilantin, Free)

Tube Type

Test ID   LAB32
EPIC Order
   PHENYTOIN LEVEL, FREE
CPT Code(s)   80186
Group/Individual Test   Individual
Laboratory   Mayo Laboratories
Tube Station Routine 30
  STAT 888
Specimen Routine: 7mL blood/Red plain tube/or Navy blue plain tube; See Comments 
 
 2 mL blood/Red plain tube
Stability
Unspun - 2 hrs
Spun and Separated Room Temp - 7 days
Spun and Separated Refrigerated - 7 days
Spun and Separated Frozen - 14 days
Availability Routine: Sent to Reference Lab
  STAT: N/A
Turnaround Time   3 days
Reference Range Therapeutic: 1-2 mcg/mL (trough, steady state)
  Toxic: > or = 2.5 mcg/mL
Comments
  • Red plain tubes must NOT contain Serum Separator Gel.
  • Specimens less than 2 mL will be canceled.

Reviewed by J. Carr on October 22, 2025

UNC Hospitals
McLendon Clinical Laboratories
101 Manning Drive
Chapel Hill, NC 27514