Home
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 dayPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been cleared or approved by the U.S. 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
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.