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Test Code BARB Phenobarbital

Specimen and Container/Tube

Specimen Type: Serum

Preferred Specimen: Red Top

Other Acceptable specimens: Serum/Gold Top, Plasma/Li-Heparin Mint Top

Specimen Stability

Storage Temperature

Stability

Room temperature

7 days

Refrigerated

7 days

Frozen

2 months

Collection Instructions

Collect specimen per standard laboratory collection procedures. 

 

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

  • Collect specimen per standard collection procedure and send to laboratory immediately. 

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Samples should be centrifuged within 2 hours of collection.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature.
  • Aliquot sample into plastic transport tube containing a minimum of 0.2 mL of specimen.
  • Samples must be sent room temperature at 15-25oC.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are clotted or grossly hemolyzed.
  • Specimens that were transported unspun/whole blood and draw time is greater than 6 hours.

Reference Values

Test

Age

Sex

Reference Range

Phenobarbital

All

All

15-40 μg/mL

Critical Values

Analyte

Unit

Low

High

Age

Phenobarbital

μg/mL

n/a

>60

All

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: 1 hour

Routine Turnaround Time: 4 hours

Testing Schedule: 24/7

Clinical Indications

Used in the diagnosis and treatment of phenobarbital use or overdose and in monitoring levels of phenobarbital.

Test Components

Phenobarbital
 

CPT Codes

80184

LOINC Codes

3948-7

Methodology

Kinetic Interaction of Microparticles in solution (KIMS) (Roche Diagnostics)

Synonyms/Keyword Search

PHNO2, PHENO, BARB, Phenobarb

Additional Information

  • Results should always be assessed in conjunction with patient's medical history, clinical examination and other findings.
  • Monitoring of the serum level of the drug is essential in order to achieve maximal seizure control while maintaining minimal blood levels to avoid negative side effects.
  • Variation in metabolism and absorption of the drug may cause levels to rise above 40 μg/mLor fall below 15 μg/mL.

Last Review Date

8/19/2024

Volume

Preferred Volume: 0.5 mL

Minimum Volume: 0.2 mL