Phenytoin, Plasma

Overview
Department	Biochemistry
Test Code	PHTN
Synonyms	Dilantin
Availability	Monday - Sunday, testing routinely available out of hours
Turnaround Time	1 - 2 hours
Stability – Add test
Specimen Requirements
Specimen	Serum Plasma
Preferred	6 mL Plain Red-Top</span
Acceptable	6 mL Li-Hep Green-Top
Unacceptable
Specimen Transportation	Sample should be ideally collected immediately before next dose
Paediatric Requirements	600 μL  Li-Hep Microtainer
Aliquot Requirements
Sample
Preferred Volume
Minimum Volume	1 mL
Aliquot Transportation
Clinical Information
Reference Intervals	Reference Range: 40 - 80 umol/L (For trough levels)
Test Method	Roche Cobas 6000 using Roche Online reagents
Advanced Notice
Patient Preparation
Comments
Please supply last dosage details (time, date and dose) where possible, and collect sample immediately prior to next dose.

Owner	Clair Crossley (Crossley1)
Last reviewed	12.09.2025
Next review	12.09.2026 (Overdue)