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Test Code PHENO Phenobarbital LAB30

Test Method

Turbidimetric Inhibition Immunoassay; Beckman DXC600


Testing is performed Monday through Sunday.

Routine: Typically completed within 4 hours after the
specimen arrives at the testing site.

Expedite: Typically completed within 1 hour after the
specimen arrives at the testing site.

STAT: Typically completed within 30 minutes after the specimen
arrives at the testing site.

Useful For

Monitoring for appropriate therapeutic concentration

Assessing compliance or toxicity

Specimen Requirement

0.5 mL serum or plasma is required.

CPT Code Information

80184 Therapeutic Drug Levels: Phenobarbital

Reference Values

10.0-40.0 mcg/mL

  • Toxic Level:  > 60 mcg/mL

LOINC Code Information

3948-7 Phenobarbital [Mass/Volume] In Serum Or Plasma

Additional Specimen Collection Information

Collect blood in a lithium heparin, green-top or
red-top tube. Serum and plasma gel tubes are not acceptable.Peak
levels should be collected between 6-18 hours after last dose.
Serum or plasma should be separated from contact with the cells
within 2 hours of collection. Specimens not centrifuged within 4
hours of collection may be rejected. Refrigerate the specimen
if unable to assay within 8 hours of collection. Samples with
>4+ lipemia must be cleared prior to analysis.