Phenytoin, Free & Total PHEN

Method(s) Quantitative Enzyme Multiplied Immunoassay Technique
Specimen Required
Collect One 6 mL plain red top tube.
Transport

2 mL serum refrigerated (Min: 1 mL). Separate from cells within 2 hours of collection.

Remarks

Patient preparation: Timing of specimen collection: Pre-dose (trough) draw-At steady state concentration.

Stability After separation from cells: Ambient: 4 days; Refrigerated: 4 days; Frozen: 1 month
Unacceptable Conditions

Citrated plasma, serum separator tubes (SST). Tubes that contain liquid anticoagulant.

Schedule Tue-Sat
Billing Code 5010485
CPTCode 80185; 80186
Notes Separate serum from cells within 2 hours of collection. Additional required information: 1. DOSE - List drug amount and include the units of measure; 2. ROUTE - List the route of administration (IV, oral, etc); 3. DOSE FREQUENCY - Indicate how often the dose is administered (per day, per week, as needed, etc.); 4. TYPE OF DRAW - Indicate the type of blood draw (peak, trough, random, etc.)
Preferred Specimen Collection Device(s)
Reference Interval
 
Effective May 16, 2016
ComponentsTherapeutic Range
Phenytoin - TotalTherapeutic: 10.0-20.0
Toxic: Greater than 30.0
Phenytoin - Free LevelTherapeutic:1.0-2.5
Toxic: Greater than 2.5
Phenytoin - Percent Free8.0-14.0%
No Appointment Necessary
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12 Patient Service Centers in Central New York.

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