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Test Code 520 Phenytoin (Dilantin)

Additional Codes

ALAB: PHY

PowerChart: Phenytoin (Dilantin) Level

MA Cerner: Dilantin Level

Test Method

Turbidimetric Inhibition Immunoassay; Beckman DxC700AU

Specimen Requirement

0.5 mL serum or plasma is required.

Additional Specimen Collection Information

Collect blood in a lithium heparin, green-top or red-top tube. Peak specimens should be collected at least 6 hours after last dose. Trough level is collected just prior to next dose. Serum or plasma should be separated from contact with the cells within 2 hours of collection. Specimens not centrifuged within 4 hours of collection may be rejected. Refrigerate the specimen if unable to assay within 8 hours of collection. Samples with >4+ lipemia must be cleared prior to analysis.

Performance

Testing is performed Monday through Sunday.

Routine: Typically completed within 4 hours after the specimen arrives at the testing site.

Expedite: Typically completed within 1 hour after the specimen arrives at the testing site.

STAT: Typically completed within 30 minutes after the specimen arrives at the testing site.

Reference Values

10.0-20.0 mcg/mL

  • Toxic Level:  > 25 mcg/mL

CPT Code Information

80185 Therapeutic Drug Levels: Phenytoin

Useful For

Monitoring for appropriate therapeutic concentration

Assessing compliance or toxicity

LOINC Code Information

3968-5 Phenytoin [Mass/Volume] In Serum Or Plasma