ARUP's Laboratory Test Directory

Phenytoin : 0090090

Mnemonic: DIL

Methodology: Enzyme Immunoassay
Performed: Sun-Sat
Reported: Within 24 hours
Specimen Required: Collect:  One 5 mL plain red.

Transport:  1 mL serum at 2-8°C. (Min: 0.2 mL)  Submit specimen in an ARUP Standard Transport Tube.

Pediatric Collection/Transport:  0.2 mL serum at 2-8°C.

Remarks:  Allow specimen to clot completely at room temperature.  Separate serum from cells ASAP. Avoid use of separator tubes and gels.

Unacceptable Conditions:  Specimens collected in separator tubes, sodium fluoride, potassium oxalate, EDTA tubes.  Hemolyzed specimens.

Stability:  After separation from cells: Ambient: 8 hours; Refrigerated: 4 days; Frozen: 1 month
Reference Interval:
0-2 months: 6.0-14.0 µg/mL
  Toxic: 14.1 µg/mL  or greater 
3 months and older: 10.0-20.0 µg/mL
  Toxic: 30.1 µg/mL or greater 
Interpretive Data: Falsely elevated phenytoin levels may occur in critically ill, uremic patients receiving fosphenytoin. 
CPT Code(s): 80185
 
 

 

 

 
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