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Test Compendium


Test Code

  • 5184

Test Synonym

  • Free Phenytoin


  • 3 mL

Minimum Volume

  • 1.5 mL

Specimen Requirements

  • Serum Or Plasma


  • Plain Red Top Tube, Transfer Tube- Serum, Green Top Tube, Transfer Tube- Plasma


  • Refrigerated

Turn Around Time

  • 3 days

CPT Codes

  • 80186
    *The CPT codes provided are based on AMA guidelines and are provided for informational purposes only. CPT coding is the responsibility of the billing entity. Please direct any questions regarding the CPT coding to the payer being billed.

Special Instructions

  • Red-top tube or green-top (heparin) tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant. Transfer separated serum or plasma to a plastic transport tube and indicate sample type. Draw specimen just prior to next dose.

Additional Information

  • 3 ml serum or plasma

Specimen Stability

  • 14 days Room temp, 14 days Refrigerated, 14 days Frozen