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Test Code Lab31 Phenytoin, Total, Plasma

Performing Laboratory

Barnes-Jewish Hospital Laboratory

Methodology

Kinetic interaction of microparticles in solution (KIMS)

Literature References:

Package Insert: Phenytoin PHNY2 Roche Corporation 02/2012

Specimen Requirements

Specimen Type: Plasma
Container/Tube: Mint-green top (lithium heparin)
Specimen Volume: Full tube


Collection Instructions: Drawn blood no earlier than 60 minutes prior to dose. Since absorption is complete by 8 hours, a specimen drawn 8 or more hours after last dose is acceptable.

Day(s) Test Set Up

Monday through Sunday

Turnaround Time:
STAT: 1 hour after receipt in laboratory 
Routine: 2-4 hours after receipt in laboratory

Test Classification and CPT Coding

80185

Reference Values

Therapeutic range: 10-20 mcg/mL

Critical result (automatic call-back): ≥30 mcg/mL

Note: Therapeutic or toxic effects of anticonvulsant drugs may occur at different concentrations in different patients, and the correlation between dose and clinical effect must be evaluated individually.

Literature Reference:

Waldman SA, Terzic A. Pharmacology and therapeutics, principles to practice. Saunders Elsevier, Philadelphia, PA: 2009.

Specimen Transport Temperature

Ambient

Additional Information

For BJH Laboratory Use Only

Alternate Tube:

1 dark green-top (lithium or sodium heparin) tube

1 lavender-top (EDTA) tube
1 red-top tube
Separator gel tube is acceptable

 

Analyte Stability:

  • Specimens must be processed within 4 hours.
  • Processed sample stability:
    • Ambient - 2 days
    • Refrigerated (2 - 8°C) - 2 days
    • Frozen (≤ -20°C) - 5 months
  • See Analyte Stability Chart under General Information for a complete list.

Laboratory Processing Instructions:

Test performed in BJH Core Lab.  Processed by automated line for delivery to the Cobas 8000. Completed specimens are stored refrigerated for 5 days. 

LOINC Code Information

Name LOINC Code
Phenytoin, Total, Plasma  3968-5