Ordering Recommendation

Use to optimize dosing and monitor patient adherence.

New York DOH Approval Status

This test is New York state approved.

Specimen Required

Patient Preparation

Timing of specimen collection: Predose (trough) draw at steady state concentration.


Gray (potassium oxalate/sodium fluoride). Also acceptable: Plain red, green (sodium heparin), lavender (K2 or K3EDTA) or pink (K2EDTA).

Specimen Preparation

Separate serum or plasma from cells ASAP or within 2 hours of collection. Transfer 2 mL serum or plasma to an ARUP standard transport tube. (Min: 1 mL)

Storage/Transport Temperature


Unacceptable Conditions

Gel separator tubes. Plasma or whole blood collected in light blue (sodium citrate). Hemolyzed specimens.


After separation from cells: Ambient: 1 week; Refrigerated: 2 weeks; Frozen: 3 years (Avoid repeated freeze/thaw cycles)


Quantitative Liquid Chromatography-Tandem Mass Spectrometry


Tue, Fri


1-7 days

Reference Interval

Effective November 16, 2015

Dose-Related Range: Prazepam (Dose: 20-60 mg/d)  (Assayed as Nordiazepam)
Nordiazepam: 100-1500 ng/mL
Toxic: Greater than 2500 ng/mL

Interpretive Data

Prazepam is not detected in serum due to its rapid metabolism to nordiazepam. Adverse effects may include dizziness, fatigue, drowsiness, ataxia, and weakness.

Compliance Category

Laboratory Developed Test (LDT)


Hotline History


CPT Codes

80346 (Alt code: G0480)


Component Test Code* Component Chart Name LOINC
0090672 Prazepam (Assay As Nordiazepam) 3977-6
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


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Prazepam (Assayed as Nordiazepam)