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Test Code VALUM (PDL Code) / DIA (Mayo Code) Diazepam and Nordiazepam, Serum

Reporting Name

Diazepam and Nordiazepam, S

Useful For

Assessing compliance


Monitoring for appropriate therapeutic level


Assessing toxicity

Method Name

High-Performance Liquid Chromatography (HPLC)

(Separate determinations are performed.)

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Serum Red

Specimen Required

Container/Tube: Red top

Specimen Volume: 3 mL

Forms: If not ordering electronically, complete, print, and send a Neurology Test Request Form (T732) with the specimen (

Specimen Minimum Volume

1.1 mL

Specimen Stability Information

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

Reject Due To


Mild OK; Gross reject


Mild OK; Gross reject


Mild OK; Gross reject


Serum gel tube

Reference Values

Therapeutic concentrations

Diazepam: 0.2-0.8 mcg/mL

Nordiazepam: 0.2-1.0 mcg/mL

Total of both: 0.4-1.8 mcg/mL

Toxic concentration

Total of both: ≥5.0 mcg/mL

Day(s) and Time(s) Performed

Thursday; 9:00 a.m.

CPT Code Information


G6031 (if appropriate)

LOINC Code Information

Result ID Reporting Name LOINC Code
8629 Diazepam, S 3548-5
2475 Nordiazepam 3537-8
2459 Diazepam and Nordiazepam 16757-7

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 U.S. Food and Drug Administration.