Phenobarbital, Total/Unbound, S/P

Luminal, Barbital, Solfoton, Donnatal, Bellatal, Phenobarbital, free and total

Test Codes

EPIC: LAB1231900, PHENOT/U/B, Quest: 3238

Department

Send Outs

Specimen Collection Criteria

Collect (preferred specimen): One plain Red-top tubes.
Also acceptable: One Lavender-top EDTA tubes or One Pink top (EDTA).

Do not use Serum Separator Tubes.

Physician Office/Draw Specimen Preparation

Centrifuge to separate serum or plasma from cells within 2 hours. Transfer serum or plasma to a plastic transport tube and maintain at room temperature (20-26°C or 68-78.8°F).

Preparation for Courier Transport

Transport: 2.0 mL serum or plasma, at room temperature (20-26°C or 68-78.8°F). (Minimum: 1.0 mL)

Rejection Criteria

• Serum Separator (SST) tubes.
• Specimens not collected and processed as indicated.

In-Lab Processing

Centrifuge to separate serum or plasma. Transfer serum or plasma to a plastic transport tube and maintain at room temperature (20-26°C or 68-78.8°F).

Transport: 2.0 mL serum or plasma, at room temperature (20-26°C or 68-78.8°F). (Minimum: 1.0 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 3 months
Refrigerated (2-8°C or 36-46°F): 3 months
Frozen (-20°C/-4°F or below): 18 months

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Quest Diagnostics, Wood Dale, IL and forwarded to NMS Labs, Horsham, PA.

Performed

Daily.
Results available in 7-10 days.

Reference Range

By report.

Test Methodology

High Performance Liquid Chromatography (HPLC). Tandem Mass Spectrometry.

Clinical Utility

Phenobarbital is a general CNS suppressant that has proven effectiveness in the control of generalized and partial seizures. Unbound drug levels are theoretically more closely correlated to therapeutic effect. This assay is used for the therapeutic monitoring and toxicity assessment of unbound phenobarbital.

CPT Codes

80184

Contacts

Last Updated

11/19/2025