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Test Code DIL or PTN Phenytoin (Dilantin®), Plasma or Serum

Methodology

Heterogenous Competitive Immunoassay

Phenytoin is an anticonvulsant that is used primarily in the treatment of seizure disorders. This test may be used to monitor for appropriate therapeutic concentration, or to assess compliance or toxicity.

Specimen Requirements

Submit only 1 of the following specimens:

 

Preferred:

Serum Gel Tube

Specimen Type: Serum

Container/Tube: Serum gel

Specimen Volume: 2 mL

Specimen Minimum Volume: 1 mL

Collection Instructions: Draw blood just prior to next dose or as specified by physician. To confirm toxicity, peak levels should be drawn 3 to 9 hours post oral dose. Spin down within 4 hours of draw.

Additional Information:

1. Date and time of last dose and time of draw are required.

2. Label specimen as serum.

 

Alternate:

Plain Red Top Tube

Specimen Type: Serum

Container/Tube: Plain, red top

Specimen Volume: 2 mL

Specimen Minimum Volume: 1 mL

Collection Instructions: Draw blood just prior to next dose or as specified by physician. To confirm toxicity, peak levels should be drawn 3 to 9 hours post oral dose. Spin down within 4 hours of draw.

Additional Information:

1. Date and time of last dose and time of draw are required.

2. Label specimen as serum.

 

Alternate:

Specimen Type: Plasma

Container/Tube: Green top (lithium heparin)

Specimen Volume: 2 mL

Specimen Minimum Volume: 1 mL

Collection Instructions: Draw blood just prior to next dose or as specified by physician. To confirm toxicity, peak levels should be drawn 3 to 9 hours post oral dose. Spin down within 4 hours of draw.

Additional Information:

1. Date and time of last dose and time of draw are required.

2. Label specimen as plasma.

Specimen Transport Temperature

Refrigerate

Day(s) Test Set Up

Monday through Sunday

Performing Laboratory

Kalispell Regional Medical Center-Chemistry

Reference Values

Therapeutic concentration: 10.0-20.0 µg/mL

Critical concentration (automatic call-back): >25.0 µg/mL

Test Classification and CPT Coding

80185