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Test Code MEPHS Mephobarbital and Phenobarbital, Serum

Reporting Name

Mephobarbital and Phenobarbital, S

Useful For

Monitoring of mephobarbital and phenobarbital therapy

Profile Information

Test ID Reporting Name Available Separately Always Performed
MBARS Mephobarbital, S No Yes
PHBRS Phenobarbital, S No Yes

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Serum Red

Specimen Required

Collection Container/Tube: Red top (Serum gel/SST are not acceptable)

Submission Container/Tube: Plastic vial

Specimen Volume: 1.2 mL

Collection Instructions:

1. Draw blood immediately before next scheduled dose.

2. Centrifuge and aliquot serum in plastic vial within 2 hours of collection.

Specimen Minimum Volume

0.7 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Red Refrigerated (preferred) 14 days
  Ambient  14 days
  Frozen  14 days

Reference Values


Therapeutic range: 1.0-7.0 mcg/mL

Toxic concentration: ≥15.0 mcg/mL



Therapeutic range

Children: 15.0-30.0 mcg/mL

Adults: 20.0-40.0 mcg/mL

Toxic concentration: ≥60.0 mcg/mL

Day(s) Performed


Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


G0480 (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
MEPHS Mephobarbital and Phenobarbital, S 97183-8


Result ID Test Result Name Result LOINC Value
89706 Mephobarbital, S 3750-7
84582 Phenobarbital, S 3948-7

Report Available

3 to 9 days

Method Name

Gas Chromatography-Mass Spectrometry (GC-MS)


If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.