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Regional Medical Lab
Test Directory


Dilantin (Phenytoin) Free and Total

Order Name DILANT F T
Test Number: 3700400
Revision Date 01/03/2022
Test Name Methodology LOINC Code
Dilantin Free
Quantitative Enzyme Multiplied Immunoassay Technique 3969-3 
Dilantin Percent Free
Calculation 10548-6 
Dilantin Total
Quantitative Enzyme Multiplied Immunoassay Technique 3968-5 
Specimen Specimen Volume (min) Specimen Type Specimen Container Transport Environment
Preferred 2 mL (1 mL) Serum Clot Activator (Red Top, No-Gel) Frozen
Instructions Timing of specimen collection: Pre-dose (trough) draw - At steady state concentration. 
Separate serum from cells within 2 hours of collection and freeze.
Unacceptable Conditions: Citrated plasma. Serum separator tubes (SST). Tubes that contain liquid anticoagulant. 
Stability:After separation from cells: Ambient: 4 days; Refrigerated: 4 days; Frozen: 1 month.
Testing Schedule Tues-Sat 
Expected TAT 2-5 Days  
Notes Reference Lab: ARUP
Test Code: 90141
Click Here to view information on the ARUP website.
CPT Code(s) 80185, 80186
Lab Section Reference Lab