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Epic Test Code LAB468 Diazepam and Nordiazepam, Serum

Additional Codes



NY State Approved


Performing Laboratory

Mayo Clinic Laboratories in Rochester

Reporting Name

Diazepam and Nordiazepam, S

Method Name

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Specimen Stability Information

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

Specimen Required

Container/Tube: Red top

Specimen Volume: 0.5 mL

Bassett Healthcare Network Clinical Laboratories Note:

Blood Tube Draw Volume
Min 50% draw volume  

Specimen Type

Serum Red

Specimen Minimum Volume

0.3 mL

Reference Values

Therapeutic concentrations

Diazepam and Nordiazepam: 200-2,500 ng/mL

Analytic Time

Same day/1 day

Day(s) and Time(s) Performed


CPT Code Information


G0480 (if appropriate)

Reject Due To


Mild OK; Gross OK


Mild OK; Gross OK


Mild OK; Gross OK


Serum gel tube


No significant cautionary statements

Specimen Retention Time

14 days


For seizures:

Serum concentrations are not usually monitored during early therapy because response to the drug can be monitored clinically as seizure control. If seizures resume despite adequate therapy, another anticonvulsant must be considered.


Toxicity is commonly seen when diazepam plus nordiazepam concentrations exceed 3,000 ng/mL. Adverse effects of benzodiazepines in therapeutic doses usually reflect the drug's pharmacology and include sedation, slurred speech, and ataxia. Respiratory depression/arrest may occur with large overdoses or following rapid IV injection with short-acting benzodiazepines.

Clinical Information

Diazepam, a benzodiazepine derivative, is an anxiolytic agent that reduces neuronal depolarization resulting in decreased action potentials. It enhances the action of gamma-amino butyric acid (GABA) by tightly binding to A-type GABA receptors, thus opening the membrane channels and allowing the entry of chloride ions. It is also used as a muscle relaxant, procedural sedation agent, and sedative-hypnotic agent to treat withdrawal states (ie, ethanol), along with other conditions (seizures).


Diazepam is metabolized to several metabolites in the liver including temazepam, oxazepam, and nordiazepam (desmethyldiazepam) and the clearance of the drug is reduced considerably in the elderly and in patients with hepatic disease.


Therapeutic assessment typically includes measurement of both the parent drug (diazepam) and the active metabolite (nordiazepam).

Useful For

Assessing compliance


Monitoring for appropriate therapeutic level


Assessing toxicity


If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.