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HelpTest Code LAB1125 Phenobarbital, Plasma or Serum
Additional Codes
| Test Name in EPIC | EPIC Test Code | Mnemonic |
|---|---|---|
| PHENOBARB | LAB1125 | PHENB |
Useful For/Utility
Use for the quantitative measurement of phenobarbital in human serum or plasma. The measurements obtained are used in the diagnosis and treatment of phenobarbital overdose and in monitoring levels of phenobarbital to help ensure appropriate therapy.
Methodology
Chemiluminescent Microparticle Immunoassay (CMIA)
Clinical Information
Phenobarbital was introduced in 1912 for the treatment of epilepsy, particularly for controlling focal motor or sensory seizures and grand mal seizures.1 Phenobarbital is bound to both plasma and tissue proteins. Monitoring serum concentrations of phenobarbital has been shown to improve patient therapy by providing physicians with a tool for adjusting dosage. In addition, because of the narrow therapeutic index and wide inter-individual variability in the rate of phenobarbital metabolism and clearance, the determination of blood levels of phenobarbital for patients receiving therapy is important.
Specimen Requirements
Specimen must be refrigerated until test is performed.
Submit only 1 of the following specimens:
Preferred:
Specimen Type: Plasma
Container/Tube: Light-green top (lithium heparin gel)
Specimen Volume: 1 mL
Specimen Minimum Volume: 0.5 mL
Collection Instructions:
1. Spin down and separate plasma from cells within two hours of draw.
2. For oral dose, draw trough level unless otherwise specified. For intravenous (IV) dose, draw trough level. To monitor effect of IV loading dose, draw 2 hours after dose is infused. If toxicity is suspected, draw level when ordered STAT.
Additional Information:
1. Avoid repeated freeze/thaw cycles.
2. If extreme lipemia-use ultracentrifuged specimen.
3. Label specimen appropriately (plasma).
Alternate:
Specimen Type: Serum
Container/Tube: Serum gel
Specimen Volume: 1 mL
Specimen Minimum Volume: 0.5 mL
Collection Instructions:
1. Spin down and separate serum from cells within two hours of draw.
2. For oral dose, draw trough level unless otherwise specified. For intravenous (IV) dose, draw trough level. To monitor effect of IV loading dose, draw 2 hours after dose is infused. If toxicity is suspected, draw level when ordered STAT.
Additional Information:
1. Avoid repeated freeze/thaw cycles.
2. If extreme lipemia-use ultracentrifuged specimen.
3. Label specimen appropriately (serum).
Specimen Transport Temperature
Refrigerate 5 days/Ambient 2 days/Frozen 6 Months
Day(s) Test Set Up
Monday through Sunday
Performing Laboratory
Chemistry-
St. Joseph's Medical Center Lab
SMDC Clinical Lab
Fargo Hospital Lab, St. Mary's - Detroit Lakes Hospital Lab
Test Classification and CPT Coding
80184
Reference Values
15-40 µg/mL