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HelpTest Code PNYG Phenytoin, Total and Phenobarbital Group, Serum
Useful For
Monitoring for appropriate therapeutic concentration of phenytoin and phenobarbital
Assessing compliance or toxicity
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| PNYA | Phenytoin, Total, S | Yes | Yes |
| PBR | Phenobarbital, S | Yes | Yes |
Reporting Name
Phenytoin, Tot and Phenobarbital, SSpecimen Type
SerumSerum Red
Specimen Required
One serum specimen (0.5 mL of serum) may be sent if using a red top tube.
Serum for Phenytoin:
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.
Serum for Phenobarbital:
Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions:
1. Serum gel tubes should be centrifuged within 2 hours of collection.
2. Red-top tubes should be centrifuged, and the serum aliquoted into a plastic vial within 2 hours of collection.
Specimen Minimum Volume
0.25 mL for 2 specimens; 0.25 mL for 1 serum red top
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 14 days | |
| Frozen | 28 days | ||
| Ambient | 72 hours | ||
| Serum Red | Refrigerated (preferred) | 7 days | |
| Frozen | 14 days | ||
| Ambient | 7 days |
Reject Due To
| Gross hemolysis | Reject |
Reference Values
PHENYTOIN, TOTAL
Therapeutic: 10.0-20.0 mcg/mL
Critical value: ≥30.0 mcg/mL
PHENOBARBITAL
Therapeutic: 10.0-40.0 mcg/mL:
Critical value: ≥60.0 mcg/mL
Day(s) Performed
Monday through Sunday
Report Available
Same day/1 daySpecimen Retention Time
1 weekPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
80184-Phenobarbital
80185-Phenytoin, total
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| PNYG | Phenytoin, Tot and Phenobarbital, S | 104596-2 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| PBR | Phenobarbital, S | 3948-7 |
| PNYA | Phenytoin, Total, S | 3968-5 |
Forms
If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.