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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.

Reference Values

10.0-40.0 mcg/mL

  • Toxic Level:  > 60 mcg/mL

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

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.