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HelpTest Code PTNF Phenytoin, Free, Serum
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Reporting Name
Phenytoin, Free, SUseful 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
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 Type
Serum RedSpecimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum Red | Refrigerated (preferred) | 7 days |
| Frozen | 14 days | |
| Ambient | 7 days |
Day(s) Performed
Monday through SundayReference Values
Therapeutic: 1.0-2.0 mcg/mL Critical value: ≥2.5 mcg/mLTest 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.Method Name
Membrane Separation/Kinetic Interaction Microparticles in Solution (KIMS)
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 |
Report Available
Same day/1 dayCPT Code Information
80186
Forms
If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.