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HelpTest Code PNYA Phenytoin, Total, Serum
Reporting Name
Phenytoin, Total, SPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Useful For
Monitoring for appropriate therapeutic concentration
Assessing compliance or toxicity
Method Name
Kinetic Interaction of Microparticles in a Solution (KIMS)
Specimen Required
Collection Container/Tube: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial within 2 hours of collection.
Specimen Type
Serum RedSpecimen Minimum Volume
0.25 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: 10.0-20.0 mcg/mL
Critical value: ≥30.0 mcg/mL
Interpretation
Dose should be adjusted to achieve steady-state total phenytoin concentrations between 10.0 and 20.0 mcg/mL.
In patients with renal failure, total phenytoin is likely to be less than the therapeutic range of 10.0 to 20.0 mcg/mL. Severe toxicity occurs when the total blood concentration exceeds 30.0 mcg/mL.
Day(s) Performed
Monday through Sunday
Report Available
Same day/1 dayTest 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.CPT Code Information
80185
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| PNYA | Phenytoin, Total, S | 3968-5 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| PNYA | Phenytoin, Total, S | 3968-5 |
Forms
If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
-Neurology Specialty Testing Client Test Request (T732)
-Therapeutics Test Request (T831)