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Test Code Billings Clinic: 4037 Dilantin® (Phenytoin), Plasma

Performing Laboratory

Billings Clinic Laboratory: Chemistry

Useful For

Monitoring Dilantin therapy

Methodology

Particle Enhanced Turbidimetric Inhibition Immunoassay (PETINIA)

Specimen Requirements

Submit only 1 of the following specimens:

Serum or plasma should be physically separated from cells as soon as possible with a maximum limit of two hours from the time of collection.

 

Plasma

  • Draw blood in a green-top (lithium heparin) tube(s) 5 to 6 hours after last dose.
  • Spin down and send 1.0 mL of heparinized plasma frozen.
  • Date and time of last dose and date and time of draw are required on request form

 

Serum

  • Draw blood in a plain, red-top tube(s) or a serum gel tube(s) 5 to 6 hours after last dose. 
  • Spin down and send 1.0 mL of serum frozen
  • Date and time of last dose and date and time of draw are required on request form for processing.

Storage/Stability

Specimen Type Temperature Time
Plasma Refrigerated 2 days
  Frozen (preferred) 5 months
  Ambient 24 hours

 

Reject Due To

  • Gross hemolysis

Reference Values

  • Therapeutic concentration:  10-20 µg/mL
  • Call-back toxic concentration value:  >20 µg/mL

Day(s) Test Set Up

Daily

Test Classification and CPT Coding

80185 - Phenytoin; total

LOINC Code Information

Reporting Name LOINC Code
Dilantin 3968-5