Phenytoin, Free

Abbrev Code:PHYFR   
Order Code:LAB5845Order Name:Percent free phenytoin panel
Synonyms:Dilantin; Free Dilantin; Unbound Phenytoin; PHYFER
Methodology:Ultrafiltration; Immunoassay
CPT Codes: 80186 x1
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

Optimal Volume:6 mL
Minimum\Peds Volume:1.4 mL
Container:Red (no gel)
Alternate Containers: 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


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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