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HelpTest Code PNYF Phenytoin, Free, Serum
Useful For
Monitoring for appropriate therapeutic concentration of free phenytoin: free phenytoin level is the best indicator of adequate therapy in renal failure
Assessing compliance and toxicity
Method Name
Membrane Separation/Kinetic Interaction Microparticles in Solution (KIMS)
Reporting Name
Phenytoin, Free, SSpecimen Type
Serum RedSpecimen 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/mLDay(s) Performed
Monday through SundayReport Available
Same day/1 dayPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| PNYF | Phenytoin, Free, S | 3969-3 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| PNYF | Phenytoin, Free, S | 3969-3 |
CPT Code Information
80186
Forms
If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.