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Test Code PNYF Phenytoin, Free, Serum

Specimen Type

Serum Red


Specimen Required


Collection Container/Tube: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 2 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial within 2 hours of collection.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Red Refrigerated (preferred) 7 days
  Frozen  14 days
  Ambient  7 days

Reject Due To

Gross hemolysis Reject

Reference Values

Therapeutic: 1.0-2.0 mcg/mL Critical value: ≥2.5 mcg/mL

Day(s) Performed

Monday through Sunday

Report Available

Same day/1 day

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

80186