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PHENYTOIN, SERUM

Synonym(s):
Lab Section Category
View write-up
Specimen Required

​3 mL plain blood

Trough levels (just before next dose) should be monitored. For suspected toxicity, draw specimen 3 – 9h after last dose. (time depends on total drug dose).

Method

​Immunoassay

Reference Interval / Value

​Therapeutic Range : From 0 day : 10.0 - 20.0 mg/L

Turnaround Time

​Mean = 4 hrs, Range: 3 – 5 hrs

Day(s) Test Set up

​Daily, 24 hrs STAT

Last Updated - 13 Jun 2025