Phenytoin, Free


Sunquest Code:PHYFR  
Epic Code:LAB5845Epic Name:Percent free phenytoin panel
Synonyms:Dilantin; Free Dilantin; Unbound Phenytoin; PHYFER
Methodology:Ultrafiltration; Immunoassay
CPT Code:80186
Turnaround Time:Routine specimens are sent to reference laboratory Mon-Fri; results are reported within 1-3 days. Stat specimens are sent to the reference laboratory 24/7; results are reported the same day.
Special Instructions:
UMMC only: Send specimens STAT to MedTox using the OnTime courier on all shifts. See Associated Links.  
Associated Links:

ROB Work Aid for MedTox, OnTime Stat Courier Request for East Core Lab



Collection Instructions

Specimen:Blood
Optimal Volume:6 mL
Minimum\Peds Volume:1.4 mL
Container:Red (no gel) (Green (lithium heparin, no gel), Green (sodium heparin, no gel))
Collection Instructions:Trough level is preferred; collect immediately before dose. It is advisable to monitor at the same time in the dosing schedule.
Causes for Rejection:Gross hemolysis; collected in gel tube. Results may be altered if collected in gel tube.


Processing and Shipping

Specimen Processing:Centrifuge and aliquot 3 mL, 0.6 mL minimum; minimum volume does not permit repeat analysis. Store in refrigerator. UMMC see Special Instructions.
Shipping Instructions:Ship at room temperature.
Test Performed at or Referral Lab Lab Sendouts  (MedTox)
Referral Lab number:98


Interpretive

Critical Range:Greater than 4 ug/mL
Reference Range:1.00-2.00 ug/mL
Use:Identify protein binding problems; therapeutic drug monitoring; evaluate toxicity.


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