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HelpTest Code PRMB Primidone and Phenobarbital, Serum
Additional Codes
CNE Order Code: Primidone
Useful For
Assessing compliance
Monitoring for appropriate therapeutic levels of primidone and phenobarbital
Assessing toxicity
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| PRIMD | Primidone, S | No | Yes |
| PBR | Phenobarbital, S | Yes | Yes |
Testing Algorithm
Includes phenobarbital determination.
Method Name
PRIMD: Immunoassay
PBR: Kinetic Interaction of Microparticles in a Solution (KIMS)
Reporting Name
Primidone and Phenobarbital, SSpecimen Type
SerumSpecimen Required
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
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 7 days | |
| Frozen | 28 days | ||
| Ambient | 72 hours |
Reject Due To
| Gross hemolysis | Reject |
Reference Values
Primidone
Therapeutic: 5.0-12.0 mcg/mL
Critical value: ≥15.0 mcg/mL
Phenobarbital
Therapeutic: 10.0-40.0 mcg/mL
Critical value: ≥60.0 mcg/mL
Interpretation
At steady-state, which is achieved approximately 2 weeks after therapy is initiated, blood levels of primidone that correlate with optimal response to the drug range from 9.0 to 12.5 mcg/mL for adults and 7.0 to 10.0 mcg/mL for children younger than 5 years.
The corresponding levels for phenobarbital are 20.0 to 40.0 mcg/mL for adults and 15.0 to 30.0 mcg/mL for children younger than 5 years.
Dosage adjustment based on blood level information is the best way to obtain optimal response to the drug.
Day(s) Performed
Monday through Sunday
Report Available
Same day/1 dayPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
PRIMD-80188
PBR-80184
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| PRMB | Primidone and Phenobarbital, S | 10547-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| PBR | Phenobarbital, S | 3948-7 |
| PRIMD | Primidone, S | 3978-4 |
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)