Alert

Effective Jan. 5, 2026: Temporary Age-Based Visitor Restrictions at UNC Health for all inpatient and waiting areas throughout its inpatient hospitals.

Read More

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